His answer was _______, so no one could make out what he meant.
| A．ambiguous | B．unconscious | C．transparent | D．explicit |
The cost of living in Glasgow is among the lowest in Britain, ________ the quality of life is probably one of the highest.
| A．since | B．when | C．as | D．while |
The sound of the birds __________happy memories of my childhood holidays.
| A．called up | B．called for | C．called on | D．called in |
In the USA, _______ Thanksgiving Day is a harvest festival．Traditionally, it is _______ time to give thanks for the harvest and express gratitude in general．
| A．the; a | B．/; the | C．/; a | D．the; the |
Measures have been taken to solve the problem, but it may be some time ____ the situation improves．
| A．since | B．when | C．unless | D．before |
Hoping he would not disturb his sleeping father, Bob stole in, ____ and waited for him to wake up
| A．didn’t speak | B．not to speak | C．not speak | D．not spoke |