In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.
| A．signal | B．chance | C．mark | D．measure |
You’ ll feel better as long as you ___ the doctor’s advice.
| A．ask for | B．give | C．follow | D．understand |
I can’t find my English book. I must ___ it at home this morning.
| A．forget | B．leave | C．have forgotten | D．have left |
--Who did you ___ in the street last Sunday?---Lin Tao, a good friend of mine.
| A．run away | B．run for | C．run into | D．run after |
Something ___ to save our earth. Do you think so?
| A．can do | B．must do | C．has to do | D．must be done |
I’ m sorry, I mistook you ___ your sister ___ mistake.
| A．for, by | B．by, for | C．by, by | D．for, for |