点P（-2，3）关于x轴对称点的坐标是（ ）。关于原点对称点的坐标是（ ）。
（-2，-3）；（2，-3 ）
正常成人潮气容积中无效腔气为（）
A.100ml
B.150ml
C.200ml
D.250ml
E.300ml
Clinical evidence began to__________, suggesting that the new drugs had a wider range of useful activities than had been predicted from experiments in animals.
A．operate
B．straighter
C．approve
D．accumulate
