Choose the best options to fill in the blanks in the following sentences

Bài tập 1: Choose the best options to fill in the blanks in the following sentences.
(Chọn phương án đúng nhất để điền vào chỗ trống trong những câu dưới đây.)
at this time yesterday?
1. What
A. were you doing B. are you doing
C. did you do
D. were you do
2. I saw the accident when I
for the bus.
A. waited
B. were waiting
C. waiting
D. was waiting
3. While people
a sudden tsunami surprised everyone with its huge waves.
A. fish
B. was fishing
C. were fishing
D. fished
4. We
money to help the earthquake victims at this time last month.
A. were donating
D. donate
B. was donating
C. donated
5. While she
in the field, the tornado came.
B. was working
C. worked
A were working
6. I
A wrote
D. is working
an essay about how natural disasters affected human's lives at 9 p.m. last night.
B. were writing
C. was writing
D. am writing