Despite their of interest, Fleming kept trying to develop chemical it would be safe and effective.
A. lack, so as to
B. lacking, so as to
C. lack, so that
D. lacking, so that
网友回答
A. lack, so as to
B. lacking, so as to
(答案→)C. lack, so that
D. lacking, so that
解析：考查短语用法。Lacking要与介词in连用；名词lack与介词of连用，表示缺少…；so as to后面不能接句子，只能接短语；so that后面接句子。句意：尽管他们缺少兴趣，但是Fleming 还是不停地发展化学品，以至于那些化学品安全有效。故C正确。