Bats (are able) to (guide them) by producing sound waves (too high) for us (to hear).A.are
Bats (are able) to (guide them) by producing sound waves (too high) for us (to hear).
A.are able
B.guide them
C.too high
D.to hear
Bats (are able) to (guide them) by producing sound waves (too high) for us (to hear).
A.are able
B.guide them
C.too high
D.to hear
Bats are able to guide them by producing sound waves too high for us to hear.
A B C D
Which of the following gives a general idea of how the noise-killing system works?
A.By producing pressure waves going in the opposite direction.
B.By mixing high frequency sound waves with low frequency sound waves.
C.By mixing new sound waves with the noise and sending them out together.
D.By making copies of tire unwanted sound waves and letting them out a little later.
Which of the following gives a general idea of how the noise killing system works?
A.By producing pressure waves going in the opposite direction.
B.By mixing high frequency sound waves with low frequency sound waves.
C.By mixing new sound waves with the noise and sending them out together.
D.By making copies of the unwanted sound waves and letting them out a little later.
The attempt to help blind people to see with sound ______.
A.was similar to the sound location system of the bats
B.led to a product that sent out sound waves of about 20,000 cycles per second
C.was experimented on a submarine
D.turned out to be a failure
A、Tom must have an absolute advantage in the production of baseball bats.
B、Jim must have an absolute advantage in the production of baseball bats.
C、Tom has a comparative advantage in the production of baseball bats.
D、Jim has a comparative advantage in the production of baseball bats.
A.who
B.will
C.their
D.in
A.one of
B.older parks
C.established
D.in
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