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

从绿色植物自身来说，制约其吸收矿质离子的因素是

①根细胞的呼吸强度②根细胞内细胞液浓度③植物体的蒸腾作用④植物自身的遗传性[ ]

A．①②

B．②③

C．③④

D．①④