A total of 264,302 people in the country were reported __________ with HIV by the end of last September.

A．to have been infected

B．to be infected

C．to having been infected

D．to have infected

同一音叉发出的声波同时在水和空气中传播，某时刻的波形曲线如图，以下说法正确的是

A．声波在水中波长较大，b是水中声波的波形曲线

B．声波在空气中波长较大，b是空气中声波的波形曲线

C．水中质点振动频率较高，a是水中声波的波形曲线

D．空气中质点振动频率较高，a是空气中声波的波形曲线