I /We don't think Tom is at home,is he?
I/We think Tom is at home,isn't he?
Lucy thinks Tom is at home,doesn't she?
Lucy doesn't think Tom is at home,does she?
当主句是第一人称I/We...时,反意问句是针对后面的从句的主、谓.
当主句的主语是其它人称时:He/She/ You/ They think/ don't think that Tom.后面的反意问句是针对前面的主句部分的主谓.