________, the text became easier for us to learn.
A. New words explained
B. New words being explained
C. New words are explained
D. New words was being explained
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Father came back, _______ a bag of money on his left shoulder.
A. he carried
B. he carrying
C. carrying
D. and carrying
二阶系统起调量与阻尼比有关吗?
A. 有
B. 没有
时域的性能指标分成哪几种?
A. 超调量
B. 调整时间
C. 峰值时间
D. 上升时间