35.----- Can you use chopsticks, John?

　 ----- ________ . I once stayed in China for two years.

A．No problem　　 　　　　　　　　　　　　　　　 B．It all depends

C．I’m sorry, but yes　　　　　　　　　 D．You can forget it

34.Since the Obama administration took office, the China-US relations ________ positive development thanks to joint efforts of both sides, President Hu said at the Nuclear Security　 Summit in Washington, April,12,2010.

A．witnessed　　 　　　 B．were witnessed　　 C．had witnessed　　 　　 D．have witnessed

33.The other day I was showing the boys the weekly chemistry experiment when, ________ I knew it, the mixture was bubbling over everywhere.

　 　 A．if　　 　　　　　　　　 B．before　　　　　　　　 C．though　　 　　　 D．unless