.Growing around the river ________ wild flowers of almost the same colour.

A．is

B．was

C．are

D．has been

60岁以上者，每增加1岁，其吸入空气时PaO比正常值减少（）。

A.1mmHg

B.2mmHg

C.3mmHg

D.4mmHg

E.5mmHg