A man does not know the difficulty of anything_________ he does it personally.
There is no reason why you shouldn’t tell the headmaster _________ that you are resigning because he has arranged your post.
—May I speak to your manager Mr. Williams at five o’clock tonight? —I’m sorry, Mr. Williams _____ to a conference before then.
______ after a long walk, Mike called and said he couldn’t come to the party.
October 1, 2009 is a special day, ________ I think, that will be remembered by all the Chinese forever.
The child, who was believed _______ by a tiger, was found in a forest.