In paragraph 5 the word "buffs" means______.
A. settlers
B. enthusiasts
C. buyers
D. manufacturers
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The passage implies that Leavitt's work on Cepheid variables would not have been possible
A. the camera as a scientific tool
B. techniques for determining the distances between stars
C. a method of measuring a star's gravitational force
D. an understanding of the chemical properties of stars
What happened in 1986？
A. Retirement stopped being practiced.
B. Age limitation in retirement was abolished.
C. Age discrimination was legally abolished.
D. Retired people were no longer entitled to pensions.
It can be inferred that Americans being approached too closely by Middle-Easterners would
A. stand still
B. jump aside
C. step forward
D. draw back
Active noise-cancellation systems require______.
A. microphones
B. microprocessors
C. loudspeakers
D. all of the above
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