【多选题】The Grand C was helpful in________.
C.
protecting the environment
D.
boosting the local agriculture
【简答题】已知f(t)=u(t)cos2t,其中u(t)为单位阶跃函数,试求f(t)的Fourier变换.
【单选题】The Grand C was first excavated in ________.
B.
the Warring States period
C.
the Spring and Autumn Period
【单选题】Mass media was born. And this ________ a whole new world.
【单选题】听力原文:M: What did you major in besides English? W: I majored in education, too. Q: What did the woman major in? (17)
B.
English and Education.
D.
Neither English nor Education.
【简答题】听力原文:Q: In order to breathe, what did the mother put over their faces? In order to breathe, what did the mother put over their faces?
【单选题】已知f1(t)=2[u(t+1)-u(t-1)],f2(t)=u(t)-u(t-2),若f(t)=f1(t)*f2(t),则f(0)=( )。
【简答题】发动机的分类方法有:按进气系统是否增压分 和 。