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第四部分阅读理解（共20小题，每小题2分，计40分）
通读下列短文，从各小题所给的A、B、C、D四个选项中选出最佳选项，并在答题卡上将该项涂黑。
I always feel sorry for world leaders busy dealing with fights between nations. When my three children were young, most days it was hard keeping my house from becoming a battlefield.
It got worse as they grew older. Three years ago, Zack, then 16, couldn’t make it through a day without making his sisters, Alex 11 and Taryn 9, angry.
My husband and I tried to be understanding the boy at such an age. We reasoned, punished, and left heartfelt notes on his bed about how he was hurting our family. His answer was “I say it because it’s true.”
I even tried telling the girls to fight back. Bad idea. Now I had three children at war. Whatever I said to them, they paid no attention. When there was no way out, I told everything to my sister, Mary, in an e-mail. She replied, “Don’t e-mail me. E-mail him.”
Our son was online every day, mailing and talking with his friends. Maybe he would actually hear me this way. I didn’t say anything different, but e-mail just took the tension away. There’d be no shouting or door banging. Zack wouldn’t feel under attack.
Zack didn’t reply for days. When he finally did, his entire message was four small words. I smiled when I read them: “You’re right. I’m sorry.”
The children still fought, of course, but Zack changed. Best of all, I now have a better way to talk with not one but three of them. I like it that they don’t tune me out as much as they used to. They like not having to listen to me shouting to them. Or as Alex says, “You’re so much nicer online.”
All I know is that the house is quiet. But we’re talking.
71. What was the trouble before the online talk in the family?
A. The writer failed to understand her daughters.
B. The children couldn’t get along peacefully.
C. The family found it difficult to keep the house clean.
D. The parents were not willing to talk with their children.
72. The writer once tried to deal with her son’s problem by _______.
A. talking with him about his pain
B. telling him about the truth of the family
C. telling her daughters to keep away from him
D. encouraging her daughters to fight against him
73. The writer e-mailed her sister _______.
A. to tell her about the family problem B. hoping she’d e-mail the boy
C. asking about child-raising D. to escape from the problem
74. The underlined phrase “tune me out” in the passage probably means _______.
A. quarrel with me B. get angry with me
C. pay no attention to me D. keep me out of their rooms
s，在某一时刻的波形如图所示，且此时a点向下运动，则 