`1.` They're not sure how to operate the new system.

`->` How to V : Làm thế nào để

`2.` I spent 4 hours reading the first chapter of the book.

`->` Spend thời gian Ving : Dành thời gian làm gì

`3.` Tennis is not as dangerous as snowboarding.

`->` SS bằng : S be as adj as S

`4.` "I will not have enough time to finish the job." He said

`->` Would V `=>` Will V

`->` Câu gián tiếp `=>` Câu trực tiếp

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`1` They're not sure how to operate the new system .

`-` S + be not sure about doing sth : Ai đó không chắc chắn về việc gì .

`2` I spent `4` hours reading the first chapter of the book .

`-` It + take + O + time + to V + O : nó tốn ai đó bao lâu để làm gì .

`=>` S + spend + time + V-ing + O : Ai đó dành bao lâu thời gian làm gì .

`3` Tennis is not as dangerous as snowboarding .

`-` So sánh ngang bằng : S1 + be + as + adj + as + S2 .

`4` ''I will not have enough time to finish the job'' , he said .

`-` Trực tiếp tường thuật : ''S + V + O'' , S + said .