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

会计核算的具体内容是各单位在生产经营和业务活动中，发生的各种各样的经济业务和( )。

A．经济活动

B．经济事项

C．经济资源

D．经济政策