题目

 — Mom, I was the first to reach the top of the mountain.      — Good job, Charlie. I’m ______ of you.     A. tired                      B.  proud                     C. sure                         D. sick 答案：B若f(x)=(ex－e－x)，g(x)=(ex+e－x)，则f(2x)等于A.2f(x)                                                            B.2g(x)C.2［f(x)+g(x)］                                             D.2f(x)·g(x)