已知平面简谐波的方程为V=Acos(Bt-Cx),式中A,B,C为止常数,此波的波K和波速为:()。
A.A
B.B
C.C
D.D
参考答案:B
解析:
平而简谐波的通用表达式为
Our math teacher ______ in our school for 20 years and he _____ here when he was 23 years old.
A.has taught, has come
B.taught, comes
C.taught, came
D.has taught, came
若使用二进制指数退避算法,发送成功概率最大的数据帧是( )
A.首次发送的帧
B.冲突2次的帧
C.冲突4次的帧
D.冲突8次的帧