问题
选择题
Tom described his father, who _______ a brave boy many years ago, as a strong-willed man. [ ]
A. would be
B. could be
C. must be
D. must have been
答案
答案：D
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Tom described his father, who _______ a brave boy many years ago, as a strong-willed man. [ ]
A. would be
B. could be
C. must be
D. must have been
答案：D
（2）（3分）此时衰减调节旋钮位于“ ” 挡，若要使此波形横向展宽，并显示出3个完整的波形，同时要求波形波幅适当大些，需要进行的操作是 （ ） 