Choose the underlined part that needs correction

IV. Choose the underlined part that needs correction.
1. She meets an old friend at a dinner party last weekend.
A B
CD
2.
There are a big traffic jam on the road to the downtown.
A
B
C D
3. The teachers had a meeting at 6 o'clock on the afternoon.
A
B
C
D
We have a smoke detector on the ceiling in each classrooms.
A
B
C
D
5. She don't know whether she left her book at school or on the bus.
C
D
4.
6.
7.
A
B
Schools in America are closed at Thanksgiving Day and the day after.
A
B
C
D
We can find out about schools in the past by looking to evidence.
A
B
C
D
8. I heard a heavy footstep on the stairs when I close my book at 9.30 p.m.
A
B
C
D
9. The students love camping on the mountain on summer holidays.
A
B
C
D
10. In some cities, people don't feel safety when going out alone at night.
A
B
C
D