如图，光滑水平面上，子弹水平射入木块后留在木块内．现将子弹、弹簧、木块合在一起作

拓展延伸。

       通过学习本单元的课文，我们了解到世界上还有不少地区存在着战争，战争给人民带来了灾难。我要就世界和平问题向国际社会呼吁，我最想说的是：

A．ZB

B．GB

C．GB/T

D．OB

通过（），我们可以得到产品的渗透水平和渗透深度、产品使用者和购买者的人口统计特征、消费者的使用习惯和购买习惯。

A.消费者使用与态度调研

B.产品概念测试

C.品牌名称定量测试

D.包装测试

The repairman told me, “No charge, Professor Pan! We’re friends.” “I’d rather pay,” I replied. “If it’s free, I can’t afford it!”

Chinese often refuse payment for professional services, insisting, “We’re friends now!” But then they show up later to ask me to tutor them in English, or get them into an American university, and I wish I’d have just paid the 30 yuan I owed them in the first place!

According to the Americans “There’s no free lunch.” meaning, there’s a price for everything, and I’m always looking around to figure out what this means.

Many of our neighbors have given us fruit or flowers or costly teas, never asking anything in return. For years, a bicycle repairman has repeatedly refused to let me pay him. “Wait until you have something major to fix!” he insists.

I mentioned to a peasant friend that I wished I had a stone mill to grind (磨) flour for bread. A month later he showed up with a beautiful mill that he’d had his uncle in the countryside carve from a solid block of granting (花岗石).

Chinese generosity is a real education for Americans like me, who would rather avoid social entanglements (纠纷) and just hand over the money. But cash can’t compensate (补偿) for the greatest gift—friendship.

When an American saw some of my friends sitting on bamboo stools under the trees, sipping tea, he said, “They must have nothing better to do.” “Actually,” I said, “they are professors, with plenty of to do. But probably you’re right in saying that, at this moment, they have nothing better to do. And neither do I”

And I joined the group. We chatted about tea and Chinese cooking and how much my boys have grown since we arrived. One man said, “They were pocket-sized when you came here. Now they’re taller than you. How time flies!”

How time flies. And Chinese are smart enough to share what they know, which they cannot keep. They freely give off their time, never too busy to help a friend. And they are teaching me, slowly, to both give and receive.

So the next time someone says, “No charge. We’re friends!” I will thank them heartily. But if they show up later asking me to tutor them in English, I’ll make sure they tutor my son in Chinese as well, because there’s still no free lunch.

69.Why did the author insist paying the repairman when he was offered free repairs?

A. Because he was an upright (正直的) man.

B. Because he didn’t know the repairman.

C. Because he thought it natural to pay for others’ service.

D. Because he didn’t want to help others in return.

70. Generally, the author thinks that _____ .

A. Chinese are generous and always ready to help their friends

B. Chinese are good at exchange of equal values

C. Chinese are free enough to drink tea and chat with their friends

D. Chinese are helpful but don’t treasure time

71. The best title of the article should be _____ .

A. Still no free lunch

B. A good lesson from the Chinese

C. True help or not

D. Learn to both give and receive        

72. Which of the following is TRUE?

A. Chinese seldom refuse payment for professional services.

B. When a peasant knew the author needed a mill, he made one for the author himself

C. The author thinks that Chinese are wise enough to enjoy their life.

D. Finally, the author changed his mind and decided to do as the Chinese do.

请举例说明处理多目标时，如何留主删次？