1, My parents spend a lot of time taking care of us although they're very busy. : Although: mặc dù

2, He told her his parents were proud of his good marks that year. : Câu gián tiếp( Lùi thì và thay đổi từ)

3, We would be healthy if the air in the city was pure. :Câu đk loại 2( If + QKĐ, would V) 

4, The monitor, who was appointed just last week, made no comment on the situation. 

5, Safety helmets have to be worn at all time. : Câu bị động( be + VPII)

1. My parents spend a lot of time taking care of us although they are very busy.

2. He told her his parent pounded of his good mark that year.(giải thích bên dưới)

3. We would be healthy if the air in the city was pure.

4. The monitor was appointed just last week who made no comment on the situation.

=> Người mà..

5. Safety helmets has been worn at all time.

Giải thích:

Câu trực tiếp gián tiếp: this thành that.

Will thành would.

Câu bị động:

Hiện tại hoàn thành: S +have/has + been+ Vp2+(by O)

Hết. Chu s bạn học tốt. Vote. Và cho mk xin ctlhn nha