`1,` The question was too difficult for him to answer.

- tobe + too+ adj+ for sb + to do sth: quá như thế nào đó đối với ai để làm gì

-> mang nghĩa phủ định

`2,` It took her father two hours to plant the trees in the garden yesterday.

- It takes+ O-chỉ người + time to do sth: Ai đó mất bao lâu để làm gì 

`3,` Diane ought to have finished the project before Tuesday.

- should have/ ought to have/must have + Vp2 : lẽ ra nên làm gì 

`4` The motor in this machine has to be cleaned once a week.

- have to + be+ Vp2: phải được làm gì 

`5,` I would rather you started work next week.

- would rather sb did sth: muốn ai đó làm gì đó