—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
—what do you think of Bill? —He is a hard-working student and he always ____himself in study.
_____ I shouted at the top of my voice _____ turn his head.
—How did you find him out?—I ______ his name by chance on the list.
---Is there any present for me ?---Of course .This necklace __you .
The gravity on the earth is much ______ that on the moon, do you know why?