The man. .when the policeman came.
A. is sleeping B. was sleeping
2. I was reading..my sisters were playing with their dolls.
A. when
C. has slept D. slept
B. at which
C. while
D. at time
3. Thanh is always .. . about the hot weather.
A. complain B. complaining
4. Nga . a letter at 8 o'clock last night.
A. write
C. complained D. to complain
B. was writing
C. is writing D. writes
5. We were studying when the telephone...
A. rings
6. When I arrived at school gate, my friends . .
A. were standing B. are standing C. will stand D. stood
7. Mrs. Chi.. .always .
A. was/ losing B. has/ lost
8. My father is . . forgetting things on the bus.
A. always
B'is ringing
C. rang
D. will ring
...her keys
C. will/ lose D. is/ losing
B. usually
C. often
D. sometimes

Bốn số lượng tử không phù hợp là:…Tại sao chọn đáp án đó…?

A. n=3, l=1, m1=0, ms= +1/2

B. n=4, l=3, m1=-3, ms= -1/2

C. n=2, l=1, m1=2, ms= -1/2

D. n=3, l=2, m1=1, ms= +1/2