四.根据短文内容,判断正(T)误(F)。 My name is Sally White . I am a school girl . My school is far from my home . Every day it takes long time to get there . The road is not flat . So I cannot go to school by bike . I often go there by bus or on foot . It takes me thirty minutes to get there by bus and an hour on foot . I must get up very early every morning . I have no time for breakfast at home . I often eat something for breakfast on the way . I don’t want to be late for school . () The school isn’t near her home .
第1题
第2题
第3题
己知x(t)的频谱函数,设f(t) = x(t)cos2t,信号f(t)的奈奎斯特率为( )。
A、8 rad/s
B、4 rad/s
C、3 rad/s
D、2 rad/s
第4题
某二阶LTI系统,y"(t)+a0y'(t)+a1y(t)=b0f'(t)+b1f(t),在激励e-2tu(t)作用下的全响应为(-e-t+4e-2t-e-3t)u(t);而在激励δ(t)-2e-2tu(t)作用下的全响应为(3e-t+e-2t-5e-3t)u(t),设初始状态同定,求:
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