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
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