20．He said he would accept the job, so we have asked him to __________ his acceptance in writing.

A．confirm　 　　　　 B．prove　 　　　　　　　 C．sign　 　　　　　　　　 D．announce　

19．When she was in trouble, I did what I could to help her. __________ my help, she wrote me a letter of thanks.

A．In honor of　 　 B．In case of　 　　　　 C．In terms of　 　　　 D．In return for