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【判断题】
闭环控制系统与开环控制系统相比主要是增加了反馈系统。A.
正确
B.
错误
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【单选题】The book, ____ are true stories about great scientists of the 20 th century, is well worth reading.
A.
which
B.
what
C.
in which
D.
of which
【简答题】Underwater cameras are helping scientists make ______, but diving expeditions are still the most useful way to gather information.
【单选题】______ the beginning of the 19th century did scientists know that all matter is made up of atoms. [ ]
A.
At
B.
By
C.
Up to
D.
Not until
【单选题】On the basis of their models, scientists are of the opinion that______.
A.
the climate of the world should be becoming cooler
B.
it will take thousands of years for the inertia of the earth's climate to take effect
C.
the man-made warming effect helps to increase the solar effect
D.
the new Ice Age will be delayed by the greenhouse effect
【简答题】_____the beginning of the 19 th century did scientists know that all matter is made up of atoms. A,At B,By C,Up to D,Not until
【单选题】With the population explosion, scientists will have to ______ new methods of increasing the world's food supply.
A.
come up with
B.
carry out
C.
lead to
D.
stick to
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