While he ________ his homework , his mother came in.
#41781
A
does
B
did
C
was doing
D
do
推荐题目
The film _________ for twenty minutes when I got to the cinema.
#40058
A
has begun
B
had begun
C
has been on
D
had been on
Great changes __________ in China in the past few years.
#36358
A
were taken place
B
took place
C
have been taken place
D
have taken place
The director wants to make sure no one will solve the mystery until it ________ at the end of the horror film.
#38260
A
is explained
B
will be explained
C
explains
D
has explained