【简答题】n. 1 [U] (AmE) all the teachers in a university, college, or school 全体教员 2 [C, usu. pl.] a natural physical or mental ability that most people have 天赋;能力;本领
【简答题】A.t[1]=u[1]∧t[2]=u[2]∧t[3]=V[4] B.t[1]=v[1]∧t[2]=u[2]∧t[3]=u[4] C.t[1]=w[1]∧t[2]=u[2]∧t[3]=V[4] D.t[1])=u[1]∧t[2]=v[2]∧t[3]=v[4]
【单选题】已知:x(t)=A[u(t)- u(t-1)] , h(t)=u(t-1)- u(t-3), 则 ( )。 A 是常数
A.
A(t-1) u(t-1)-A(t-4) u(t-4)
B.
(t-1) u(t-1)-(t-2) u(t-2) -(t-3) u(t-3) +(t-4) u(t-4)
C.
At u(t)-A(t-1) u(t-1)-A(t-2) u(t-2)-A(t-3) u(t-3)
D.
A(t-1) u(t-1)-A(t-2)u(t-2)-A(t-3)u(t-3) +A(t-4) u(t-4)