Qian Xuesen tried many times _________ he found the solution to the puzzle about space technology.
#31596
A
after
B
before
C
since
D
when
推荐题目
Reality is not the way you wish things to be, nor the way they appear to be, _________ the way they actually are.
#32565
A
as
B
or
C
but
D
and
_______ the sports meet will be held depends on the weather.
#31262
A
Whenever
B
If
C
Whether
D
That
Jack is a common person, _______, I think, that will be found everywhere.
#34357
A
whom
B
who
C
one
D
he