---May I speak to your manager Mr.Willians at five o'clock tonight?"---"I'm sorry, Mr.Williams _______ to a conference before then."
-Has Tommy finished his homework yet? -I have no idea; he ____ it this morning.
Mrs. Brown was much disappointed to see the washing machine she had _____ went wrong again.
Last term our maths teacher set so difficult an examination problem _____ none of us worked out.
_____ all the inventions have in common is ______ they have succeeded.
-What shall we have for dinner tonight? -Oh,I don’t care. ____. It’s your job to come up with the menu,so get on with it.