When I walked past his house, I heard him _______.
#50226
A
to sing
B
sang
C
sings
D
singing
推荐题目
It’s important __________ fire.
#50876
A
to care
B
be careful
C
to be careful
D
to be careful with
Huangshan is a good place to _____.
#49361
A
go sightseeing
B
go for a sightseeing
C
go to sightseeing
D
go in sightseeing
— I tried       it out in this way, but I failed.— Why not       it in some other ways?
#50281
A
to work; try doing
B
to work; try to do
C
working; try to do
D
to work; to try doing