1. It is useful to learn english. (It is + Adj + to Verb)

2. If she works hard, she will pass the exam. (Câu ĐK loại 1) 

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1. Tom has just been seen. (Câu bị động ở thì hiện tại hoàn thành)

2. That book is not as expensive as this one. (So sánh bằng: S + be (not) + as + Adj + as + S)

3. Tuan, who lives next door to me is very intelligent (sử dụng đại từ quan hệ "who" thay thế cho chủ ngữ)

4. If the weather weren't bad, we could go out. (Câu ĐK loại 2, nói về 1 điều không thể xảy ra ở hiện tại)

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1. Unless someone puts the coal in, the fire will go out. (Unless = if not)

2. It took Ba 2 hours to help his mother with the housework yesterday. (It takes (took) + O + khoảng thời gian + to Verb)

Writing

1/ It is useful to learn English 

2/ If she works hard,  she will pass exam. 

II

1/ Tom has just been seen ( by us)

2/ That book is not as expensive as this book. 

3/ Than,  who lives next door to me,  is very intelligent 

4/ If the weather is good, he can go out

III

1/Unless someome put the....,  the fire will go out

2/ It took Ba 2 hours to help his mother with the housework yesterday