原因
Why the explosion occurred was _____ the laboratory attendant had been careless.
Why the explosion occurred was \_\_\_\__ the laboratory attendant had been careless.
The reason _____ they died was lack of medical care.
The reason \_\_\_\__ they died was lack of medical care.
是否承认社会意识在社会发展中的重要作用，是划分历史唯物主义和历史唯心主义的标准。
是否承认社会意识在社会发展中的重要作用，是划分历史唯物主义和历史唯心主义的标准。
为什么说人民群众是历史的创造者？群众路线和群众观点基本内容是什么？
为什么说人民群众是历史的创造者？群众路线和群众观点基本内容是什么？
I decided to stop and have lunch, _____ I was feeling quite hungry.
I decided to stop and have lunch, \_\_\_\__ I was feeling quite hungry.
It was _____ it raised many difficult questions that the book took a long time to come out.
It was \_\_\_\__ it raised many difficult questions that the book took a long time to come out.