Here are the correct answers based on the context:

1. **C. doing** (My little brother used to **do** his homework early in the evening.)
2. **A. obey** (If we obey the rules, there are no more accidents.)
3. **C. take care of** (You should **take care of** right and left when you go across the road.)
4. **C. go** (Hurry up or we can’t **go**.)
5. **D. by bus** (I usually go to school **by bus**.)
6. **A. by foot** (I ride my bike **by foot**.)
7. **C. transport** (The public transport in my town is good and cheap.)
8. **C. spend** (I **spend** me a very long time to go home.)
9. **B. lasts** (When there is a traffic jam, it **lasts**.)
10. **C. cycling** (Yesterday Richard and Peter **cycled** round West Lake. It took them an hour.)
11. **C. helmet** (Cyclists and motorists have to wear a **helmet** when they ride a motorbike.)
12. **B. mask** (He forgot to give a **mask** before he turned left and got a ticket.)
13. **D. sign** (All drivers have to obey the **sign** strictly.)
14. **A. traffic rules** (A traffic **rules**.)
15. **B. traffic lights** (We should wait for the traffic lights **before** we cross the street.)
16. **C. turn yellow** (A signal will **turn yellow**.)
17. **B. fasten** (Drivers have to **fasten** your seatbelt whenever they drive.)
18. **D. put** (I used to **put** marbles when I was young, but now I didn’t.)
19. **D. didn’t use to play** (I didn’t use to **play** it from your house to the nearest bus stop?)
20. **C. How far** (How **far** is it from your house to the nearest bus stop?)

Let me know if you need help with anything else!