We _______ play on this road. There is too much traffic. 

So many people violate traffic regulations that we ____ put too much emphasis on the importance of traffic safety. 

He________sleep，although he tried to，when he got on such a hunt for an idea until he had caught it.    

The first question was difficult, but the rest were pretty easy.

It is recommended that the project ________ not be started until all the preparations have been made.