Did your classmate accept your invitation?——No, he ____ refused.

﹣Do you know about the scientist Tu Youyou﹣Yes，she won the 2015 Nobel Prize in medicine because of her great______．

“____either you or he to go there” –“_____is.”

The question that puzzled us is _____ we can get rid of the air pollution in the area.

Well_____ remember the day I ______ a wild tigar.