单项选择题

A. They go only a short way.B. They are easier to keep ……

Air pollution is caused by many things. Great clouds of smoke come from factories. Cars send smoke and fumes into the air. Burning waste fills the air with bits of dirt. Even burning leaves add smoke to the air. Sometimes, planes cannot find their landing spots through smoke. Smoke of all kinds is bad to breathe and can do great harm to the body.
Still, we cannot live without air. We must find a way to clean the air we have.
In time, we may have factories that are run by atomic energy. Our cars may run on smoke-free electric power. Scientists are also working on new ways to help the oil burned by cars from making fumes. Waste may be burned in the sand on ocean floors.
These changes might keep our air clean in the years to come. But until then, many scientists are looking for ways to make air cleaner now.

Why would electric cars cut down on air pollution().

A. They go only a short way.
B. They are easier to keep clean.
C. Electric power has no smoke.
D. Electric cars need no energy.

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单项选择题4().

A.angry
B.rich
C.patient
D.bitter

单项选择题It may be inferred from the passage that ______.

A. the ditch was along a quiet country road
B. the accident happened on a clear warm day
C. the police helped Mr. Johnson get out of the ditch
D. Mr. Johnson had a tender wife and was well attended

单项选择题Which of the following is true according to the passage().

A. Clinton broke ground for the canal at both ends.
B. Clinton started building the canal before he became governor.
C. All parts of the canal were completed at the same time.
D. Construction of the canal took eight years.

单项选择题What do we know about Jonathan

A. He is a good fame hunter with various abilities.
B. He is such a brave fighter that any criminal will feel afraid.
C. He is an expert on security, not interested in running a company.
D. He is a regular kid but does something unusual.

单项选择题Scientists are now working on ways to ______.

A. keep planes from :flying
B. bury sand on ocean floors
C. stop air pollution
D. burn leaves without smoke