—It’s necessary ____ our environment(环境).  —I agree with you. 
#50553
A
protect(保护)
B
protecting
C
to protect
D
protects
推荐题目
Although we’ve learned English for years, we have trouble _____ the       foreigners.
#50181
A
understand
B
to understand
C
understanding
D
of understanding
It’s important             exercise every morning.
#50836
A
to take
B
taking
C
takes
D
to taking
It’s easy __________you to say sorry, but remember __________ be late again.
#50925
A
for; not to
B
for; don’t
C
of; not to
D
of; to
 Lucy decided _____ a new computer. 
#49105
A
buy
B
to buy
C
buying
D
bought