---What on earth are the police busy with? ---They have been looking into how the plane crash _______.
The geography teacher told his student that the earth ________around the sun .
_________useful advice it is ?
John rushed out in a hurry,the door .
----Why are you late for school ?----Because our car _______ halfway to the destination.
With a lot of difficulties ___ , they went to the seashore and had a good rest.