问题 问答题

一木块漂浮于50℃时的KNO3饱和溶液中(见图A),当温度改变时(不考虑由此引起的木块体积的变化),木块排开液体的体积(V)随时间(t)发生了如图B所示的变化或如图C所示的变化.由此分别推出温度的改变方式是______或______(填“升温”或“降温”).同时可分别观察到烧杯底部KNO3晶体______或______(填“增多“或“减少“).

答案

由函数图象B看出木块排开水的体积增大,说明溶液的密度减小,密度减小的原因是溶液中的溶质减少,当温度降低时,KNO3饱和溶液会析出溶质,同时溶液中的固体增多.讨论函数图象B时的情况正好与之相反,此处不再列举.

故答案为:降温;升温;增多;减少.

阅读理解

The 30-mile road that runs through the mountains of Willie Valley makes most drivers′ hands sweat. But Andersen, a 46-year-old father of four, wasn’t expecting any trouble on the road last New Year’s Eve, when he set off for a ski trip to the Bear Mountains with nine-year-old daughter Mia, four-old son Baylor, and nine-year-old neighbor Kenya. Andersen had driven through the Valley hundreds of times over the years.

The weather was fine. But the higher they drove, the more slippery the road became. Rounding a sharp U-turn, Andersen saw a heavy truck off the road and immediately hit his brakes. In a minute, the car was going at 25 miles per hour down the mountain before falling down from a ten-foot dam into the extremely cold Logan River.

The crash had broken a few windows, and within seconds, the car was filled with water. “It was frightening that we were going fast into deep water,” remembers Andersen, a soft-spoken manager.

Having lost all sense of direction, Andersen began to search the freezing water for the kids. Mia had been right next to him in the front seat; now, in the blackness, he couldn’t find her. “I thought, if I don’t get out, maybe none of us are going to get out.” Andersen got out of his seat belt, swam through a broken window, and, deeply and quickly, breathed air at the surface. That’s when he saw a group of men, about ten in all, appear at the top of the dam. One after another, they rushed down into the water. Helping onto safety all the three children, they began to shout at the father, “Who else is in the car?”

Andersen says respectfully, “It was like the sight of angels.”

小题1: What might be the main cause of the car accident?

A.The bad weather.

B.The high dam.

C.The sudden brake.

D.The heavy truck.小题2: Andersen didn’t expect any trouble on the road because _____.

A.he was familiar with the road

B.he was good at driving

C.his hands didn’t have sweat

D.the weather was fine小题3: What can be learned from the last paragraph?

A.Andersen lost consciousness in the water.

B.Strangers helped Andersen out of the car.

C.Andersen liked Mia most among the children.

D.Strangers teamed together to save three children.小题4:The underlined sentence is to express Andersen’s feeling of being _____.

A.tired

B.excited

C.doubtful

D.thankful小题5:Which of the following can be the best title of the text?

A.Stay calm when in trouble

B.Drive rounding a U-turn

C.Miracle rescue from a river

D.Mystery of the Bear Mountains

单项选择题