我国邮政编码采用的是()结构。
参考答案:四级六位制
如图甲所示是一列沿+x方向传播的简谐横波在t=0时的波形图,已知波速v=2 m/s,质点PQ相距3.2 m。求:
(1)在图乙中画出质点Q的振动图象(至少画出一个周期);
(2)从t=0到Q点第二次振动到波谷的这段时间内质点P通过的路程。
—Do we have to wear our school uniforms tomorrow?
— I think so. We _____ the coming-of-age ceremony in the afternoon.[ ]
A. will be attending
B. have attended
C. attend
D. attended