it's been found that some types of oil are really bad for he
1个回答

hasn't it

前面是主从复合句,反意问句的动词和主语要和主句中的主谓语(这里是it's been found )保持对应关系.

前肯后否,所以用hasn't it

注意:it's been found =It has been found 是现在完成时的被动语态,问句中时态要一致

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