The government has taken measures air quality.
| A．to improve | B．improved |
| C．being improved | D．to be improved |
It isn't cold enough for there _____ a frost tonight, so I can leave Lim's bike out safely.
| A．would be | B．being | C．was | D．to be |
Johanna waited at the bus stop for nearly an hour ___ the bus finally arrived.
| A．when | B．unless | C．before | D．after |
No bread eaten by man is so sweet as _____ earned by his own labor.
| A．one | B．that | C．such | D．what |
Elizabeth has already been admitted to Beijing University her wildest dreams.
| A．at | B．beyond | C．within | D．upon |
Because he works in a remote area, he visits his parents only ______.
| A．occasionally | B．partly | C．practically | D．once |