Nowadays scientists are working hard to find out ______ to do with air pollution.
#37100
A
how
B
why
C
when
D
what
推荐题目
We all feel           after hearing of the           news.
#35623
A
excited;excited
B
exciting;exciting
C
excited;exciting
D
exciting;excited
               workers in the factory              over two thousand.
#43491
A
The number of; is
B
The number of; are
C
A number of; is
D
A number of; are
Simon always feels sure about his own ability, he is so ______ 
#43106
A
energetic
B
outgoing
C
imaginative
D
confident