`1.` It's is very important to keep the environment.

`-` Form: It's + be + adj + (for sb) + to V-inf + ...

`2.` The time machine will be shown to the public when they finish it.

`-` Bị động thì TLD: S + will + be + VpII + (by + O)

`3.` He was delighted that he received his aunt's letter.

`-` Sau "that" là một mệnh đề S + V

`4.` People recycle old car tires to make shoes and sandals.

`-` Bị động thì HTD (Bị động `->` Chủ động)

`-` S + am/is/are + VpII + (by + O) `->` S + V(s/es) + ...

`5.` I'm very sad not to be accepted in that group.

`-` Form: S + be + adj + (not) + to V-inf + ...

`6.` I haven't spoken to her for three years.

`-` Form: S + have/hasn't + VpII + to V-inf + ... + for + time

`->` It's + time + since + S + last + V2/V-ed + ...

`7.` Tam used to type fast.

`-` V + adv (fast vừa là adv, vừa là adj. Trong câu này thì là adv)

`-` Form: S + used to + V-inf + ...

`8.` My father asked me to turn down the radio for him. 

`-` Form: S + told/asked/... + Object + to V-inf + ...

`9.` It is Lan's fifteenth birthday next week.

`10.` When did you last use the pen?

`-` Form: When + did + S + last + V-inf + ...?