______ on ten years of observation and study, the theory shows that every one dreams every night, whether they realized it or not.

— What made your skin look so terrible? — _______ to the sunlight for a long time. 

He used to ______ games on the Internet, but now he is used to _______ a walk after supper. 

We didn’t have much difficulty _______ the company.

The crowd cheered wildly at the sight of Liu Xiang, who was reported ____ the world record in the 110-meter hurdle race.