如图所示，甲为某一简谐波在t=1.0s时刻的图象，乙为甲图中C点的振动图象．则下列说法正确的是（　　）

A．甲图中B点的运动方向向右

B．波速v=6m/s

C．要使该波能够发生明显的衍射，则障碍物的尺寸应远大于4m

D．若该波能与另一列波发生稳定的干涉，则另一列波的频率为1Hz

根据所给图片，完成下面对话。

Tom: Who's your math teacher?

Sarah: Mr Zhao.

Tom: What's he like?

Sarah: 1______________________________

Tom: Who's your English teacher?

Sarah: Miss Sun.

Tom: Is she young?

Sarah: 2______________________________

Tom: 3______________________________

Sarah: No, she's active.

Tom: Who's your Chinese teacher?

Sarah: Mr Liu.

Tom: Is he strict?

Sarah: 4______________________________ 

         But he's very 5______________________________.