When I saw my teacher nodding _______ to me, I calmed down and went on with my performance.

If a person takes drugs, they will slow down his thinking and ________ turn off his brain. 

Much to my surprise, the eight-year-old boy       fixed my computer within ten minutes．

She is quite a different girl _____ she was five years ago.

The special dance，Gangnam Style，is ________ popular all over the world and was even performed in the White House.