did you know that it's been found in laboratory testing that some types of oil are reallybad foir us?我想问,第一个that启什么作用,第二个that又是什么意思,什么作用
问题描述：
did you know that it's been found in laboratory testing that some types of oil are really
bad foir us?
我想问,第一个that启什么作用,第二个that又是什么意思,什么作用
答
第一个that 是宾语从句的that 没有意思 起连接的作用
第二个that是定语从句的that 指代的是先行词 也是连接的作用
你是初三的吧 我也是
答
第一个that是引导的宾语从句，know that +宾语从句
第二个that是主语从句，形式主语是it，而that后面的部分是真正的主语
答
这是个复合句,可以拆分成三个句子：1 did you know ；2 it's been found in laboratory testing ；3 some types of oil are really bad foir us
第一个that是是宾语从句的引导词,第二个是复合从句引导词