—Is your mother still a teacher? —______.
| A．Yes, she was | B．She didn’t use to | C．No, but she used to | D．No, but she used to be |
The U. S．declares it has the best medical technology in the world，but quite a lot of Americans have no __________to health care service．
| A．devotion | B．entrance | C．access | D．introduction |
The DiaoYu Island have been part of China’s territory since ancient times, __________as important fishing grounds of Taiwan.
| A．served | B．serving | C．to serve | D．having served |
Sun Yang, a young Chinese swimming talent, ___________several gold medals before 2012 London Olympics.
| A．won | B．has won | C．had won | D．were to win |
The government has taken some measures to solve the shortage of electricity, but it may be some time ____________ the situation improves.
| A．since | B．when | C．unless | D．before |
Mary had to go to a meeting，so she left her children ___________ at home.
| A．playing | B．played | C．to play | D．having played |