______ environmental damage is done, it takes many years for the ecosystem to recover.
#73217
A
Even if
B
If only
C
While
D
Once
推荐题目
I will put the book________you placed it and make a mark at the place________I put it.
#67077
A
where；at which
B
at which；at which
C
where；which
D
at which；where
That fellow hung around for hours and, ______ was worse, kept me from doing my work.
#71843
A
that
B
where
C
as
D
which
–Do you know _______?--- Someone wants to find his dog back.
#70398
A
what the notice says
B
what the notice writes
C
what is the notice written
D
what does the notice say
While Helen __________ the guitar, her mother came in.
#41299
A
was playing
B
is playing
C
played
D
plays
Scientists say it will be five or six years _____ it is possible to test this medicine on human patients.
#68451
A
before
B
that
C
since
D
when