Today I didn't go to the library because I needed to assisthelp my parents with their works. Today I didn't go to the library because I needed to help my parents with their work.

Today, I didn't go to the library because I needed to assist my parents atheir works. Today, I didn't go to the library because I needed to assist my parents at work.

Today I didn't go to the library today because I needed to assist my parents with their works. I didn't go to the library today because I needed to assist my parents with their work.

He needs to moves the heavy machine and prepares for many steps before starting work. He moves the heavy machine and prepares many steps before starting work.

In english, to sound like a native speaker, it is sometimes better to cut out words from a sentence (depending on the context).

He needs to move the heavy machines and prepares for many steps before work. He needs to move the heavy machines and prepare for many steps before work.

My mother is the one who usually assists him. My mother is the one who usually assists him.

When I or my siblings or I are on thea long vacation, we will go to work with my parents. When my siblings or I are on a long vacation, we will go to work with my parents.

When Ime and/ or my siblings are on the long vacation, we will go to work with myour parents. When me and/ or my siblings are on vacation, we go to work with our parents.

Use ‘me’ instead of ‘I’ unless you are referring to someone else first; like “Harry and I” or if you are saying ‘I am’. You wouldnt say ‘I are’ or ‘I is’

When I or my siblings or I are on thea long vacation, we will go to work with myour parents. When my siblings or I are on a long vacation, we go to work with our parents.

AlEven though I am sometimes I'm sovery exhausted after going home, I still feel happy when we meet some very kind clients. Even though I am sometimes very exhausted after going home, I still feel happy when we meet some very kind clients.

I think "even though" sounds better in this context.

Although sometimes, I'm so exhausted after going home, I still feel happy when we meet somclients who are very kind clients. Although, I'm so exhausted after going home, I still feel happy when we meet clients who are very kind.

You shouldn’t use two connectives side by side, unless you are saying ‘but because’ or ‘and because’

Although sometimes I'm so exhausted after goingby the time I get home, I still feel happy when we meet some very kind clients. Although sometimes I'm so exhausted by the time I get home, I still feel happy when we meet some very kind clients.

Today's client gave us nine drink bottles of drinks and three bowls of red bean soup. Today's client gave us nine drink bottles and three bowls of red bean soup.

I think that ‘drink bottles’ sounds better, although ‘bottles of drink’ would be acceptable too!

Yesterday my younger sister justwas complaineding that the refrigerator of our home didn't have any drinks, now the situation is totally different. Yesterday my younger sister was complaining that the refrigerator of our home didn't have any drinks, now the situation is totally different.

Yesterday, my younger sister just complained that the refrigerator ofin our home didn't have any drinks, now the situation is totally different. Yesterday, my younger sister complained that the refrigerator in our home didn't have any drinks, now the situation is totally different.

If you are talking in the past, of something that happened a while ago, you wouldn't say it ‘just’ happened.

YJust yesterday my younger sister just complained the refrigerator of our home didn't have any drinks,at there weren't any drinks in the refrigerator but now the situation is totally different. Just yesterday my younger sister complained that there weren't any drinks in the refrigerator but now the situation is totally different.