They boy is an excellent student, and not once in these years ___caught being late.

A．has he got

B．does he get

C．did he get

D．will he get

关于血液pH值的叙述，不正确的是（）

A.血液正常pH值为7.35～7.45

B.血液pH＜7.35为酸中毒

C.血液pH＞7.45为碱中毒

D.根据pH值改变可确定代谢性还是呼吸性酸碱失衡

E.测定血液pH值时误差应不超过+0.005～±0.01