The old teacher lay wide awake on his bed, __________ all the problems he had to deal with the next day.
In the past several weeks, many cities in Northern China________from heavy fogs, causing great inconvenience to people.
--Which car is better, the red one or the black one? --I prefer the red one, but it is really a matter of personal________.
A lot of dirty clothes require ________ so she will not go out shopping this weekend.
--What shall we do tonight then? --________ --whatever you want.
John began to study French last Sunday. ____________