请看下面的题目：
“Your phone number again? I _________ quite catch it.” “It’s 4331577”
A. didn’t               B. couldn’t             C. don’t                D. can’t

【分析】此题容易误选C，认为此处要用一般现在时态，表示现在“没听清对方的话”。其实，此题答案应选A，根据上文的语境“请把你的电话号码再说一遍好吗?”可知“没听清对方的电话号码”应是在说此话以前，故应用一般过去时态。请看以下类似试题：

(1) “Mr Smith isn’t coming tonight.” “ But he _________.”
A. promises              B. promised              C. will promise          D. had promised
答案选B，“他答应(要来)”应发生在过去。

(2) “Hey, look where you are going!” “Oh, I’m terribly sorry. _________.”
A. I’m not noticing    B. I wasn’t noticing   C. I haven’t noticed   D. I don’t notice
答案选B，“我没注意”是对方提醒之前的事，现经对方一提醒，当然注意到了。

(3) “Oh it’s you ! I _________ you.” “I’ve had my hair cut.”
A. didn’t realize         B. haven’t realized     C. didn’t recognize    D. don’t recognized  答案选C。“没认出是你”是说此话之前的事，说此话时显然已经认出了对方。

(4) “What’s her new telephone number?” “Oh, I _________.”
A. forget                   B. forgot                   C. had forgotten        D. am forgetting
此题应选A，从语境上看，“忘记”的时间应是现在，即指现在不记得了。

(5) “Since you’ve agreed to go, why aren’t you getting ready?” “But I _________ that you would have me start at once.”
A. don’t realize          B. didn’t realize         C. hadn’t realized       D. haven’t realized
答案选B。“没意识到”是对方提醒之前的事。

(6) “It’s twelve o’clock, I think I must be off now.” “Oh, really? I _________ it at all.”
A. don’t realize      B. haven’t realized     C. didn’t realize         D. hadn’t realized
答案选C。“没意识到”是在听到的话之前的事。