There will still be lots of challenges if we are to ______ garbage in a short time．（ ）
| A． |
clarify |
B． |
justify |
C． |
satisfy |
D． |
classify |
Many people who live along the coast make a living _______ fishing industry.
| A． |
at |
B． |
in |
C． |
on |
D． |
by |
If the new safety system _______ to use, the accident would never have happened.
| A． |
had been put |
B． |
were put |
C． |
should be put |
D． |
would be put |
People______better access to health care than they used to,and they're living longer as result.
| A． |
will have |
| B． |
have |
| C． |
had |
| D． |
had had |
Jim has retired, but he still remember the happy time _______ with his students.
| A． |
to spend |
B． |
spend |
C． |
spending |
D． |
spent |
The little problems ______ we meet in our daily lives may be inspirations for great inventions.
| A． |
that |
B． |
as |
C． |
where |
D． |
when |