The American people will never forget the 9.11 event and the psychological trauma __________ caused to hundreds of thousands of common households.

The chairman thought ___ necessary to invite Professor Smith to speak at the meeting . 

—— Why did he let you repeat his instruction time and time again? —— ＿＿＿＿＿＿that I remember what was＿＿＿＿＿after he went out. 

—Could I smoke here?—I’d prefer _______if you don’t smoke in front of the children.

Some say one thing, but ____.