1.In my city - Hanoi, traffic jams are one of the biggest problems. Every day, the streets become very crowded during rush hours because there are too many vehicles. People often have to wait for a long time to move just a short distance. This problem makes everyone feel stressed and tired. Moreover, it causes people to be late for school or work. I think the government should provide more public transportations to solve this problem.

1.Did you watch a documentary about electric buses on TV last night?

2.: Drivers should obey traffic signals to avoid accidents.

1.Although the traffic was heavy, they arrived at the airport on time.

2. How about going to the cinema to watch the new action film tonight?

3.Travelers should arrive early at the station before taking high-speed trains.

a. Tổng số học sinh là:

15+20+10+5=50 học sinh

b) Tỉ lệ học sinh có học lực giỏi là: 15 : 50 = 30%;

Tỉ lệ học sinh có học lực khá là: 20 : 50 = 40%;

Tỉ lệ học sinh có học lực trung bình là: 10 : 50 = 20%;

Tỉ lệ học sinh có học lực yếu là: 5 : 50 = 10%;