1 A

2 D

37 If we plant more trees, the air will be fresher

38 If we use fewer cars, we will reduce pollution

39 How often does your father play tennis?

40 How will you travel to the moon?

3. If you don't put on your coat, you will cactch a cold

4. If she does't fall over, she will not break the plantes

1. A. subject           B. Study             C. suncream       D.turning

2. A. care               B. prepare          C. here                D.square

3. A. toilets             B. kitchens         C.tables               D.pens

4. A. close              B. nose              C.flower              D.cold

5. A. these              B. there             C. thank               D. those

2 năm vì 2021-2019=2 năm

C. 24,25 ; 24,13 ; 38,62

My class is bigger (big) than yours

2. The weather this autumn is worse (bad) than last autumn.
3. Fruit juice is better (good) than coffee.

C vì chu vi hình vuông là 32 và chu vi hình tam giác là 24 nên 32-24=8

a) (-125).4 = -500

b) (-4).125 = -500

c) 4.(-125) = -500