翻译：事实上,你知道吗,实验发现一些油类是对我们非常不宜的.
第一that引导的宾语从句指 it’s been found in laboratory testing that some types of oil are really bad for us
第二个that引导的从句some types of oil are really bad for us 这一事实指的是前面句子中 it's当中的it
从句套从句 剥洋葱一层层分析咯