急如意令：英语知识运用的问题There are thirteen or more of them, and if ___

急如意令：英语知识运用的问题
There are thirteen or more of them, and if ____is missing a deficiency disease becomes apparent.
A. any B. some C. anything D. something
When the work is well done , a climate of accident-free operations is established _____ time lost due to injuries is kept at a minimum.
A. where B. how C. what D. unless
解释一下意思,并说明为什么要选这个而不是其他项