He’s trained hard for the last two years. It is ______ he did so well at the track and field meet yesterday.

    A. no problem       B. no wonder        C. no doubt         D. no way

—How long do you think it is ________ he arrived here?

　　　　—No more than half a year, I believe.

　　   A. when　　　　 B. that　　　　　C. before　　　　D. since

—How long do you think it is ________ he arrived here?

　　—No more than half a year, I believe.

His writing is so confusing that it's difficult to make out________ it is he is trying to express.

A．that         

B．how  

C．who        

D．what

22. “How long do you suppose it is _______ he left for Japan?” “No more than half a month.”

A. when   B. before    C. after D. since