已知5x+1=y+1（x，y均大于0），那么x与y[ ]

A．成正比例    

B．成反比例  

C．不成比例

I know Mr Brown； we ＿＿＿＿＿＿ to each other at an international conference.

A．are introduced

B．have been introduced

C．were introduced

D．had been introduced