如图为沿+x方向传播的一横波在某时刻的波形图象，那么关于图中的a质点，正确的说法是（　　）

A．此时刻a质点的加速度正在逐渐增大

B．此时刻a质点的速度正在逐渐增大

C．a质点沿波的传播方向的位移正在增大

D．a质点沿波的传播方向的速度正在增大

(湘郡生试题)   I was really surprised to find out that the first public showings of wireless TV transmissions took   41   way back in 1925. It took another three years before there was any regular public broadcasting.   42  , I think people must have found   43   quite a delight when color TV was first broadcast in 1929.   44   , within the next 65 years, people would be able to choose   45  to watch from a   46  of 200 different channels because   47 cable TV. It is reported   48  in 1998, 66 percent of households in the USA had cable TV.