— I’m sorry, sir. I can’t finish the work on time.
— Never mind. ________, the work is quite difficult.
A. At least B. For instance
C. After all D. First of all
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
