After years of research, he found the key ____ differences between species.
#5237
A
to explain
B
to explaining
C
of explaining
D
explaining
推荐题目
Internet is an important _____ for people to get the latest news.
#5628
A
source
B
origin
C
resource
D
cause
The advertisements in newspapers help to cut the _____ of making the newspaper.
#6657
A
price
B
pay
C
costs
D
value
Many people，especially children，are encouraged by Jackie Chan to learn kungfu to develop their good________.
#5572
A
talent
B
games
C
characters
D
language
Opinions of that kind are best kept to yourself, and not voice＿＿＿＿＿．
#7202
A
by public
B
in public
C
in a public
D
in the public
I tried to persuade him to give up the foolish idea, but in ________, and now he begins to regret.
#7190
A
vain
B
turn
C
return
D
case