You say the bridge is safe but I shall take care _____. [ ]

A. even though

B. of course

C. after all

D. at last

下列哪一项不属于蒸腾作用的意义[ ]

A．降低叶面温度

B．促进水的吸收和运输

C．增加空气湿度

D．增强呼吸作用