15. When Madam Curie did the experiment again, she was more careful where she _____ a mistake.
A.made | B.has made | C.was making | D.had made |
Sometimes they may play to passers-by in the street or subway so that they can earn some______ money for themselves or to pay for their instruments.
A.certain | B.extra | C.various | D.unusual |
The band about 1970, but happily they reunited in the mid1980s.
A.broke up | B.broke down | C.broke out | D.broke in |
As a result these endangered animals may even .
A.die away | B.die down | C.die out | D.die off |
I’m protecting myself mosquitoes.
A.from | B.in | C.on | D.at |
What must be done if wildlife protection is?
A.success | B.succeed | C.successful | D.to succeed |