I hear the birds _______.
#51349
A
sing
B
to sing
C
sings
D
singing
推荐题目
—Before he went abroad, he spent as much time as he ____ English. 
#50421
A
could learning
B
learned
C
to learn
D
could learn
My uncle is used to        for the children in poor areas.
#49405
A
raise money
B
raised money
C
raising money
D
raises money
We shall  never give up ______ for even one day. 
#49951
A
studying
B
study
C
to study
D
studies