22. — When did you last see your first teacher?
— On_____Friday last June, at_____celebration of her 40th year of teaching.
| A．a; the | B．a; a | C．不填; the | D．不填; a |
Carbon dioxide, which makes a ______ between us and the sun, prevents heat from getting out of the atmosphere easily, so the earth is becoming warmer.
| A．difference | B．comparison | C．connection | D．barrier |
In much of the animal world, night is the time ______ for sleep—pure and simple.
| A．set aside | B．set down | C．set off | D．set up |
Butterflies ______ a sweet liquid produced by flowers, which bees and other insects collect.
| A．carry on | B．feed on | C．put on | D．focus on |
According to the law, all foreigners have to ______ with the local police within two weeks of arrival.
| A．associate | B．dispute | C．negotiate | D．register |
Michelle found a job as a high school teacher which _____ spending quite a lot of time with students.
| A．enjoys | B．involves | C．practices | D．suggests |