Every evening the students go to bed at 10:30______ and the lights are turned off.
| A．at once | B．on purpose | C．at present | D．as usual |
Sweet memories __________ as I looked at the pictures __________ were taken at the beach last summer.
| A．took out; which | B．crowded in; which |
| C．ended up; that | D．dropped by; that |
When the expression first came into being, people refused to use it but __________ they began to accept it.
| A．usually | B．gradually |
| C．frequently | D．unwillingly |
Willie's wife never gives him pocket money until he __________ clearly how he will spend it.
| A．has explained | B．explained |
| C．will explain | D．is to explain |
Can you explain __________ the sun goes down in the west?
| A．why is it that | B．why it is that |
| C．how it is that | D．how is it that |
What an unforgettable experience ！ I'll write it down __________ it is still fresh in my memory.
| A．since | B．while |
| C．after | D．until |