11. The beam that is ________by a laser differs in several ways from the light that comes out of a flashlight.
A) emitted C ) motivated
B) transportedD) translated
12. We booked rooms at the hotel ________we should find no vacancies on our arrival.
A) wheneverC) since
B) if D) lest
13. Modern forms of transportation and communication have done much to ________the isolation of life in Alaska.
A) break throughC) break into
B) break downD) break out
14. We know through painful experience that freedom is never by the oppressor; it must be ________by the oppressed.
A) demandedC) required
B) commanded D) requested
15. Color and sex are not relevant ________whether a person is suitable for the job.
A) on C) to
B) for D) with
參考答案:12题应该选 D . "lest"有”以免；以防”的意思，后面接 should+动词原形．如果选 C 的话 should 不符合语法规则．
