With the loss of labor,the old farmers ________at home had to choose less laborintensive crops.
--Why don't you try your best to get on the bus?—I tried to , but I could, it started moving.
My study of biology has ___ much of my spare time, ____ it has given me a great deal o enjoyment.
The doctor will be free ___.
__ is known to everybody, the moon travels round the earth every month.
---I drove to Zhuhai for the air show last week.---Is that ___ you had a few days off?