Here is my answer to the question in today’s writing practice.:

This type of phrase is usually concluded by a colon to indicate that the indicated item follows it.

Yes, I think people will be spending more money on smartphones in the future.

Here I think the tense feels more natural in the simple future.

Also,nd since we can do a lot of things by using a smartphone, so it is becoming an essential item for our lives.

"smartphones" would also work here instead of "a smartphone" but then you would need to change "it is" to "they are"

"And since" feels like a better connector to the previous sentence. Because "since" is used at the start, the "so" is not needed later

In such situationAs a result, the developers of smartphones makes the models more functional according to users’ expectations, and eventually they cost muchend up costing more.

I feel that "in such a situation" isn't a natural connector to the previous sentence, so changed it to "as a result".

"cost much" should be "cost more". In this sentence I would also suggest adding the phrase "end up" to indicate that this is the conclusion of a process - thus "cost" is changed to "costing"

Hence, in the future, as people come to value smartphones more, they will spend muchore money on it.them.

"in the future" isn't wrong, but keeping the sentence simpler is best. "as people come to value smartphones more" already indicates a future result, so it feels redundant to point it out again.

Also, we can do a lot of things by usingwith smartphones (or with a smartphone), so it is becoming an essential item forin our lives.

In such situations, the developers of smartphones makes the model more functional according to users’ expectations, and eventuallywhich makes theym cost muchore.

Hence, in the future, as people come to value smartphones more, they will spend muchore money on it.

Also, we can do a lot of things by using a smartphone, so it is becoming an essential item for our lives.

In such situations, the developers of smartphones makes the models more functional according to users’ expectations, and eventually they cost muchore.

Hence, in the future, as people come to value smartphones more, they will spend muchore money on it.

Also, we can do a lot of things by using a smartphone, so it is becoming an essential item for our lives.

Almost had it... :)

In such situation, the developBecause of this, the makers of smartphones makeskeep making the model more and more functional according to users’ expectations, and e. Eventually, they cost muchstart to cost a lot.

1. "Because of this" makes it easier to connect the idea between this sentence and the previous one.
2. These days,"developer" tends to imply someone writing software, as opposed to hardware (which phones are). "Maker" is thus the more appropriate word to use.
3. At this point, the sentence was already getting long, and it makes more sense to declare the idea of increasing costs in a separate sentence, anyway.

Hence, in the future, as people come to value smartphones more, they will be spend muching more money on ithem.

I kept the "Hence", but some people find it a bit stiff, and would instead replace it with "That's why", or even omit it altogether.

Do you think people will spend more money on cell phones?

Without a phrase like "in the future," this sentence sounds vague/awkward

Almost all adults have a smartphones these days.

Technically "all adults" goes with "smartphones," "every adult" goes with "a smartphone"

Also, we can do a lot of things by usingwith smartphones, so it isthey are becoming an essential items for our lives.

Maybe "tools" instead of "items"? Or just "... they are becoming essential for our lives."

In such situations, thsmartphone developers of smartphones makes the models more functional according to users’ expectations, and eventually they cost mucha great deal.

In what situation, do you mean?

Hence, in the future, as people come to value smartphones more, they will spend muchore money on it.