The students _______ their homework carefully when the teacher walked into the classroom quietly.
#36148
A
do
B
did
C
are doing
D
were doing
推荐题目
 Beijing ________ a lot over the years. Now it has become one of the biggest ______ in the world.
#38242
A
changes; cities
B
changed; city
C
has changed; cities
D
changed; cities
The lamb _________already. It_ __________for 2 days.
#41729
A
has died , has been dead
B
died, has been dead
C
has been dead, died
D
died , has died