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

With the help of the new technology, you __ e-mail your friends by mobile phone.

We used to work in the same office and we _________ have coffee together.

That man over there _____ be Mr Wang . He has gone to Yushu. 

 —Can you play the violin? —_____. But I can sing.