英文选择,条件状语从句.请简单说明.Pure naphtha is highly explosive if ____to an open flame.A.it exposed B.exposed C.it were exposed D expose it

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英文选择,条件状语从句.请简单说明.Pure naphtha is highly explosive if ____to an open flame.A.it exposed B.exposed C.it were exposed D expose it
英文选择,条件状语从句.请简单说明.
Pure naphtha is highly explosive if ____to an open flame.
A.it exposed B.exposed C.it were exposed D expose it

英文选择,条件状语从句.请简单说明.Pure naphtha is highly explosive if ____to an open flame.A.it exposed B.exposed C.it were exposed D expose it
B
方法一:条件状语从句可省略主谓直接以过去分词代替.本题中if it is exposed= if exposed
方法二:排除法,A中少谓语.D错误明显.C中混淆了真实条件句和虚拟条件句的区别.不用 虚拟形式,因为该句是真实条件句.

选B.exposed
Pure naphtha is highly explosive if (it is) exposed to an open flame.