He was in two minds about the chance, which resulted in letting _____ slipping through his fingers. [ ]

A. that

B. one

C. them

D. it

关于鼠疫疫情的环境措施，以下说法正确的是（）

A、灭蚤是杜绝鼠疫流行的重要措施、灭鼠后还要再次灭蚤

B、消毒是防止鼠疫扩散的重要措施、尤其对肺鼠疫尤为重要

C、一般棉衣被褥使用蒸汽消毒

D、以上均正确