Some very common things such as    to the sun for a long time will do harm to people's skin and even cause skin cancer

A student in our school will be immediately sent home if he is found __________ computer games at night.

I would appreciate________back this afternoon so that we can reach an immediate decision.

_________ by the beautiful scenery of the west Lake, the foreigners decided to spend another two days in Hangzhou. 

      to be the best one in the group, she had an opportunity to enter for the final competition.