单项选择题
A.8cm B.16cm C.30cm D.0
A.(1/2)π B.π C.2π D.无法确定
A.y=Acosω[t-(x-L)/u] B.y=Acosω[t-(x+L)/u] C.y=Acosω[t+(x+L)/u] D.y=Acosω[t+(x-L)/u]
A.1/3 B.1/4 C.2/5 D.2/7
A.0.973 B.0.027 C.0.954 D.0.982
A.1 B.2 C.3 D.4
A.(-1,1) B.(-1,1) C.(3,7) D.(4,5)
A.e-1 B.1-e C.(1/2)(e-1-1) D.(1/2)(1-e-1)
A.0 B.-2 C.2 D.4