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【简答题】
已知某线性系统幅频特性A(ω)=1/(1+0.01ω 2 ) 1/2 ，特性φ(ω)=-arctan(0.1ω)，现测得某激励的稳态输出为y(t)=10sin(30t-π/2)，t的单位为s。试求系统的输入信号x(t)；若用该系统进行测量，要求振幅误差在5%以内，则被测信号的最高频率应控制在什么范围内?
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【单选题】听力原文：W：I hear that you work part—time at a supermarket．What do you do there? M：I work in the produce section．I also stock shelves．Sometimes when it really gets busy，I help at the check out counter． Q：...
A.
He works at the meat counter.
B.
He delivers groceries to customers.
C.
He serves as a cashier.
D.
He stocks shelves.
【单选题】The reason was _____ I was busy with my work at that time.
A.
why
B.
because of
C.
that
D.
what
【简答题】I first met Lisa three months ago .She _______(work)
at a store factory at that time.
【简答题】Revise the underlined part to achieve parallelism: Leonardo da Vince was known both as an inventor and painting pictures . Leonardo da Vince was known both as an inventor and _____ ________.
【单选题】The tone of the author to Leonardo da Vince is______.
A.
critical
B.
neutral
C.
curious
D.
praising
相关题目：
【单选题】The reason was _____ I was busy with my work at that time.
A.
why
B.
because of
C.
that
D.
what