The little child usually felt frightened at night, so not until ___________.
| A．did he fall asleep his mother left the room |
| B．he fell asleep had his mother left the room |
| C．did he fall asleep did his mother leave the room |
| D．he fell asleep did his mother leave the room |
As well as costing the Middle East dearly in terms of human life, conflict! (冲突) _______ the region around $ 12 trillion since 1991, according to a report by the Strategic Foresight Group.
| A．is also cost | B．had also cost | C．will also cost | D．has also cost |
At no time, of course, ______ anyone to separate Taiwan from the motherland in any name or by any means.
| A．will we allow | B．we will allow | C．will we be allowed | D．we will be allowed |
What _______ public is concerned about is whether medical workers and scientists will be able to find _______ cure for this new disease after the vaccine is tried on _______ volunteers.
| A．不填; 不填; 不填 | B．the; the; 不填 | C．the;不填; the | D．the; a; the |
Because of the Russian gas limit to Europe, attempts _______ to use botanical fuel as a source of power.
| A．have made | B．having made | C．are being made | D．will be making |
Chinese exports have been hit hard by falling world demand, with millions of workers _______ to their villages after the factories that employed them closed down.
| A．returned | B．returning | C．have returned | D．return |