问题 选择题

放在水平地面的一块铁,它受到的重力是G,地面对它的支持力是N,它对地面的压力是F,则其中属于一对平衡力的是(  )

A.N和G

B.N和F

C.G和F

D.以上的答案都不对

答案

因为铁块静止在水平面上,并且铁块受到竖直向下的重力和竖直向上的支持力作用,因此重力G和支持力N是一对平衡力.

故选 A.

阅读理解

I was telling my boy Sonny the story of the hare (兔子) and the tortoise (乌龟). At the end I said, “ Son, remember: Be slow and steady (镇定的), and that will win the race. Don’t you think there’s something to learn from the tortoise?”

Sonny opened his eyes wide, “Do you mean next time when I’m entering for the 60-metre race I should wish that Billy, Tony and Sandy would all fall asleep halfway?”

I was shocked, “But the tortoise didn’t wish that the hare would fall asleep!”

“He must have wished that,” Sonny said, “Otherwise how could he be so foolish as to race with the hare? He knew very well the hare ran a hundred times faster than he himself did.”

“He didn’t have such a wish,” I insisted. “He won the race by perseverance (坚忍不拔的), by pushing on steadily.”

Sonny thought a while. “That’s a lie,” he said. “He won it because he was lucky. If the hare hadn’t happened to fall asleep, the tortoise would never have won the race. He could be as steady as you like, or a hundred times steadier, but he’d never have won the race. That’s for sure.”

I gave up. Today’s children are not like what we used to be. They’re just hopeless.

小题1:The writer argued (辩论)with his son because ______________.

A.he liked tortoises while his son liked hares

B.they disagreed about whether the tortoise was foolish

C.he tried to teach his son a moral (品德) lesson but the son had totally different opinion

D.he liked the story of the hare and the tortoise while his son didn’t.小题2:Sonny believed that the tortoise ______________.

A.won the race by his own hard working

B.took a risk (冒险) by agreeing to run a race

C.was not given a fair chance in the race

D.in fact did win the race luckily小题3:Billy, Tony and Sandy must be_______________.

A.boys who were unknown to Sonny’s father

B.boys who Sonny has run races with before

C.boys who Sonny has never raced with before

D.boys who Sonny did not expect to race with again小题4:The writer thinks that his generation (一代人) ______________.

A.are cleverer than Sonny’s generation

B.have the same ideas about life as Sonny’s generation

C.are more hopeful than Sonny’s generation

D.have different ideas about life from Sonny’s generation小题5:According to the passage, who do you think learnt a lesson?

A.The tortoise

B.Sonny

C.The hare

D.Sonny’s father

单项选择题