问题描述：
without doing 可以放句首?
_____ how to get to the factory where his son worked,he went to the police for help
A Not knowing
B Without knowing
选A还是B
_____ how to get to the factory where his son worked,he went to the police for help
A Not knowing
B Without knowing
选A还是B
问题解答：
我来补答展开全文阅读