Today I can't write about academic writing here because I left my self-study course book is being kept onon the/a work table at the office and I don't remember what the next exercise whatis about.

“Is being kept on” is ok, but it sounds like you’re saying that you’re kind of being forced to keep it there, such as if someone else wanted it to stay there, opposed to saying that you forgot to bring it with you so now it’s just been accidentally left behind there.

“The” kind of puts more emphasis on the work table, and it implies that it’s like the main one in your office. You could also use “a”, which kind of just says that there are many work tables at your office, and you just left it on one of them.

Alternatively, if it actually belongs to you (like it’s where you do your work), then you could say “my”.

I also think “desk” sounds a little more natural than “work table”, but I guess it kind of depends on what kind of table it is. If you use “my”, then I’d say “desk”. Of course, if it’s like a big table that’s used for meetings or eating or something like that, “work table” would probably be more appropriate.

I don’t really know how to explain this next part well. Usually, “what” would go earlier rather than later in a sentence/clause.

The next part might be really confusing since I also got confused just writing it:
The main exception might be if you were to say something like “I don’t know what”, which could also be expanded so then “what” would be the start of a new idea (e.g. I don’t know what I should write about)
Basically you would kind of say “what (something/someone) (verb/action)” most of the time.
(But this isn’t an actual rule - it’s just the best way I could think of to try to get my idea across - so don’t actually actively try to follow it when writing).

So in your example, the “something” refers to “the next exercise” and the “verb/action” would be “is about”.
In the random example I gave, the main idea is “what I should write about”, while “I don’t know” just adds more information and turns the idea into a sentence, just as the other parts of your sentence do.
Someone = I
Action/verb = should write about.

I hope some part of that makes sense and helps.

That’s why I decided to jointell you inabout one of my memories.

You need a verb after “that” (so the verb would be “is”, making it “that’s”)
“Join you in my memories” makes it sound like the reader was already in your memories, and you are joining them afterwards.
Of course that doesn’t really work well because “in my memories” would kind of be used to describe something you remember (so if you remember a red hat, a red hat is in your memory/memories), and you don’t really actively decide on who can be in your memories (except for if you actually change your memory to something more desirable, so you can forget something that wasn’t so pleasant. In this case though, you wouldn’t describe it in that way either).

“About my memories” is ok, but it would be used if you were sharing multiple things that you remember. Here, it looks like it would be more accurate to say “about one of my memories”, since it looks like you’re just describing one memory with lots of detail.

This summer I took a course (that is) called 'Open Water Diver' is called by PADI.

So this is making me realise that maybe my comment about “that” always (or even nearly always) being followed by a subject in what I think was one of your other texts was incorrect, so I’m really sorry about that. I think I was probably using what I’ve learnt about French a little too much (because in French, there’s a word which would act as “that” and can only be followed by a subject).


The “that is” in my suggestion is optional, so you can decide whether or not you add it.

You could also move “by PADI” immediately after “took a course”.

I also agree with what someone else said about writing the full name for something followed by the abbreviation in brackets the first time you talk about them. Then after you do that, every other time you talk about them you can just use the abbreviation.

During the period of studycourse my friend and I had been reading a course book, taking thereceived instrauctions and doing in diving and did ours dives; after all that, we passed our exam and earned theour certificates.

“Period of study” feels very unnatural. “Course” is a lot more natural and well understood.

I think the “had been…” structure you were using originally would sound better if you were only talking about what you did during the course (without any reference of what happened afterwards), but even then it would still sound a little weird. If someone was to say that it would make me think that some crime had happened surrounding the course and someone was trying to recount it (of course that’s probably more my personal interpretation than the actual meaning).

Using “take” with “instructions” feels very weird to me and I’m not 100% sure of what it means. I think “received instruction” might be a little better though, and you could also add “in diving” afterwards. This would basically say that you were instructed on how to dive (which is also another way you could say it).

“After all” is used less to say that something is a consequence of or happened after something else, and more to kind of conclude a discussion. Adding in “that” would make it clear that you passed the exam and earned your certificates.

Instead of “after all that”, you could also say “then”.

I also don’t really feel like the semicolon is needed since it’s main purpose here would be to show connection between the two sentences, but “then” or “after all that” already shows connection. It also feels weird having those words after a semicolon.

I think “our certificates” sounds better. “The certificates” would probably work better if you said a little about what the certificates were for.

Imagine, that you only just started to study and the firstmain thing isyou known by you will be is that everything is different under water (when you suddenly have to start trying to dive. You’re thrown into this whole new world).

You don’t really need any punctuation after imagine.

If you want to use “only”, then something like “you only just started to study” is probably the best option.
Otherwise you can just remove “only” from your original sentence.

The much more natural way of saying “the first thing is known by you” is “the first thing that you know”.

I changed a lot of it to sound a little more dramatic because usually if a sentence starts with “imagine” then the sentence will describe some kind of really dramatic/interesting/engaging situation. For this reason, it would also sound better to add some kind of action (which is what I suggested in brackets at the end). For a better flow into the next sentence, something like “you’re thrown into this whole new world” followed by descriptions of how this is the case would be needed. The descriptions would be needed because otherwise it doesn’t make sense to start the next sentence with “so”.

When you dive under the grottoes and exhale, the bubbles rise up and attached to the ceiling.

“Attached” can be used as an adjective or the past tense of “attach”.
It doesn’t make sense to use “attached” as a verb here because none of it is about the past (it’s more of a general fact).
So to use “attached”, you would be using the adjective form in which case you would need to say “are attached”. However that doesn’t really flow that well with the rest of the sentence since the rest of it is describing the actions of the bubbles, while “are attached” suddenly jumps to how they look after they rise up. It also doesn’t really work that well since you say that when you exhale, this happens, which would mean that verbs sound a lot better.
Because of this, “attach” is probably the best option.

It looks like a lot of puddles hanging over your head.

You would need an article before “lot of puddles”, so you would be choosing between “a” and “the”. “The” would only be used if you were describing a very specific lot (or group) of puddles, which you aren’t here. Because of that, you would choose “a”.

You could say “it looks” or “they look”.
“It looks” concentrates on how it (the overall scene) looks.
“They look” concentrates on how they (the bubbles themselves) look.

Believe me, seeing it was such an amazing expierience.

When using “such” to emphasise the quality of something (here you’re using it to emphasise how amazing the experience was), you would use “a” or “an” afterwards.

I hope ithis was an interesting fact for you.

Alternatively: “I hope you found this fact interesting” or “I hope this fact was interesting for you”.
I like how the first alternative option (“I hope you found…”) feels the most.

“This” sounds better than “it” here.

You would also need to say “a” or “an” after “was” because “fact” is a noun which goes afterwards, and is what “this” is referring to. (So if “fact” wasn’t after “interesting”, then you wouldn’t need the article.

Today I can't write about academic writing heretoday because I left my self-study course book is being kept onon the work table at the office and I don't remember what the next exercise whatis about.

To further shorten the sentence a bit, you could write "office work table" to convey that's where you left it.

That why I decided to join you inshare some of my memories instead.

Adding "instead" here helps transition to a new topic.

This summer I took a course thatcalled 'Open Water Diver' is called by PADI.

I'm not sure what "PADI" is here and had to look it up. If your readers are unfamiliar with an initialism or acronym, it's helpful to write it in full the first time it appears. For example: "This summer I took a course called 'Open Water Diver" by the Professional Association of Diving Instructors (PADI)."

During the period of studycourse, my friend and I had been reading aread the course book, taking theook instrauctions, and doingid ours dives; a. After all that, we passed our exam and earned the certificates.

Another way I might write the first sentence here is, "During the course, my friend and I studied the course book, attended lectures, and did actual dives."

It was a great and fascinating challenge at the same time.

I think this works, but "Great" and "fascinating" are both positive, so adding "at the same time" hits my ear as superfluous. "It was a great and fascinating challenge" has more punch.

As a contrast: "It was a difficult but fascinating challenge" conveys that it was hard but worthwhile.

The next step was to dive three times into the open sea.

The sentence is good, but did these dives happen before or after the certificates were earned?

I want to tell you about one unique case: when we were diving in the underwater grottoes.

This sentence is good, but did this also happen before or after the certificates were earned?

Also: grotto diving is super scary and dangerous! You're very brave! I've read so many stories of divers getting into dangerous situations!

Imagine, you only start to study and the first thing is known by you will beWhen new divers first start diving, the first thing they learn is that everything is different under water.

When you use "Imagine" to start a sentence, you're inviting the reader into your world. It's better to follow it with a description or to paint a picture.

"Imagine: you secure your diving equipment, then slip below the surface of the water. You can now move in three dimensions, and you are no longer at the top of the food chain. You've entered a new world, and know everything is entirely different."

So, iIt's absolutely true.

I adjusted this sentence to flow a little better with the correction I made in the previous sentence.

When you dive under the grottoes and exhale, the bubbles rise up and attached to the ceiling.

Believe me, seeing it was such an amazing expirience.

I hope ithis was an interesting fact for youexperience for you to read about.

Since you invited the reader into your memory earlier, you're more conveying an experience than a fact.

Today I can't write about academic writing here because my self-study course book is being kept on work tableon my desk at the office and I don't remember what the next exercise whatis about.

That why I decided to join you in my memoriesshare memories with you.

This summer I took a course thatby PADI called 'Open Water Diver' is called by PADI.

During the period of studyThroughout the course, my friend and I had been reading a course book, takfollowing the instrauctions and doing ours dives; after all that, we passed our exam and earned theour certificates.

I want to tell you about one unique case: when we were diving in the underwater grottoes.

Imagine, you only start to study and the first thing isyou known by you will be is that everything is different under water.

When you dive under the grottoes and exhale, the bubbles rise up and attached to the ceiling.

I hope it was an interesting fact for you.