When you are planting trees, the trees ________ straight in the hole.
#36844
A
must put
B
must be put
C
are putting
D
is put
推荐题目
The guests were _________ in the front rows ________ to the president attentively.
#36726
A
seating; listened
B
seating; listening
C
seated; listened
D
seated; listening
What          at that time ? ---Playing football.
#39891
A
did you do
B
do you do
C
were you doing
D
are you doing