_______ is even important is ______ as the earth cooled down, water began to appear on its surface.
To keep healthy, Professor Johnson __________cycling as a regular form of exercise after he retired.
— Why was Fred forced to leave school?— Because he was__________of cheating in the English exam.
__________not to miss the meeting at 4 p. m.,the manager put down his work at once and set out for the City Hall.
-Have you got all the lights __________yet?-Yes, everything is ready for the party.
The boy wanted to go on a trip to Tibet alone,but his mother told him ___________.