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
网友回答
A. lacking；in order to
B. lack；so that
C. lack；so as to
D. lacking；so that
解析：由第一个空格前的their可知，要填名词，所以用lack；第二个空要填连词，才能引导句子。故只有B项符合题意。