Despite their __________ of interest, Fleming kept trying to develop the chemical ___________ it would be safe and effective.

A．lacking; in order to

B．lack; so that

C．lack; so as to

D．lacking; so that

与环境人口容量呈负相关的因素是

A．资源量

B．科技水平

C．生产能力

D．消费水平