问题 选择题

下列说法,你认为正确的是(  )

A.人类利用的能量都是通过化学反应获得的

B.现代化学技术可在只有水的条件下生产汽油

C.CO2会使全球变暖,所以大气中CO2越少越好

D.在使用乙醇等新型燃料时,也要注意可能造成的环境污染

答案

人类利用能量开发和利用既不凭空产生,也不凭空消失,必须遵循能量守恒定律.

A、人类利用的能量都是通过化学反应获得的,这个说法是错误的.尽管人类需要的能量大多数是通过化学反应获得的,但是也不排除物理变化为人类提供能量的可能.比如:太阳能;风能;潮汐能等等属于物理变化,同样会有能量的释放,故A错误.

B、现代化学技术可在只有水的条件下生产汽油,汽油属于碳氢化合物,而水属于氢氧化合物,不符合质量守恒定律,故B说法错误.

C、CO2会使全球变暖,所以大气中CO2越少越好,此说法不妥.尽管二氧化碳是导致全球变暖的主要原因,但是大气中的二氧化碳也是绿色植物进行光合作用的原理之一,二氧化碳参与了自然界中的物质循环,所以C错误.

D、在使用乙醇等新型燃料时,也要注意可能造成的环境污染.比如乙醇的生产过程中同样会有一些有害的气体生成,乙醇燃烧时,同样会产生更多的二氧化碳气体等问题,必须值得考虑.故D正确.

故选D

完形填空

The bell for class rang. All the students took out their  1  , waiting for the teacher. Our Chinese teacher, Miss Liu, had told us before that we were going to write a composition 2  class.
A minute passed, and another,   3  the teacher didn't appear. We began to wonder what the matter with her was. Was she ill? Or had she forgotten about the class?    4  could tell. Soon some students began to study other subjects, some students began to talk and even made  5  .
About ten minutes later, the door opened and Miss Liu   6  came in, smiling. She didn't say sorry to the class. We felt   7  angry. The teacher often told us never to be late for class and said it was   8  manners to be late. She also said that if we were late, we should make an apology (道歉)   9  at once or after class. But now she was late and had kept the whole class waiting for such a long time and didn't even tell us the reason. It was unfair. At this moment, Miss Liu picked up a piece of chalk(粉笔) and     10     "Teacher IsLate" on the blackboard and said that was the topic of our composition today. All of us smiled and understood what the teacher meant.
小题1:
A.desks B.seatsC.booksD.chairs
小题2:
A.at B.inC.on D.to
小题3:
A.butB.andC.or D.so
小题4:
A.SomebodyB.EverybodyC.Anybody D.Nobody
小题5:
A.voices B.sounds C.noises D.notes
小题6:
A.at lastB.at firstC.at all D.at times
小题7:
A.littleB.less C.a littleD.much more
小题8:
A.good B.bad C.nice D.fine
小题9:
A.neitherB.not only C.both D.either
小题10:
A.read B.wroteC.spokeD.said
不定项选择