—Where’s Jill?
—She ________ in the office. I saw her there just now.
| A．may be | B．must be |
| C．can be | D．should be |
When you are swimming, ________ your ears. You can use earplugs (耳塞) to stop water getting into your ears.
| A．take after | B．take part in |
| C．take off | D．take care of |
Turn off the water while you ________ your teeth or washing your hands.
| A．were brushing | B．brush |
| C．are brushing | D．brushed |
It ________ about eight minutes for sunlight (阳光) to travel from the sun to the earth.
| A．takes | B．spends |
| C．costs | D．pays |
Talk to your teacher and you will get help ________ you have a problem.
| A．unless | B．if |
| C．until | D．so |
We have friends to help us fight against pollution, and trees are one of ________.
| A．themselves | B．they |
| C．their | D．them |