IV

1.What were you doing at this time yesterday?

=> dấu hiệu yesterday

2.Poisonous gases are pumped into the atmosphere every day.

=> thì hiện tại tiếp diễn

3.I’m not used to walking so far , no I must stop to rest for a while.

=> Cấu trúc: Uesd to + Ving

4. If we use energy-saving bulbs, we will save a lot of money.

5. His joke made me laugh a lot.
V.

1. There are a lot of changes in our city in the past ten years

=> a lot of=>many

2. If we go on to litter, the environment will become seriously polluted

=>go=>went

3. We'll never catch then up if you walk as slow as that

=>never=>∅

5. Let's not go to the park if it will rain tomorrow

=>
IV/
1. were you doing
-> at this time yesterday (QKTD, was/were S Ving?)
2. are pumped
-> bị động HTĐ is/am/are V3/ed
3. walking/to rest
-> be used to Ving: quen làm gì
-> stop to V: dừng để làm gì
4. will save
-> câu đk loại 1: If S Vs/es, S will V
5. laugh
-> make/made sb V(giữ nguyên): khiến/làm cho
V/
1. A -> there have been
-> in the past ten years (HTHT, S have/has V3/ed)
2. A -> littering
-> go on Ving: tiếp tục làm gì
3. D -> slowly
-> walk là động từ -> cần so sánh bằng của trạng từ as adv as
4. D -> rains
-> Let's (not) V if S Vs/es