根据首字母选择单词的适当形式填空:9g;X;t'U'm'u6z6z/u7g5|5N
I have a pen friend,and we always send e/I4g.G,U0a7t4x7]6hto each other by computer.9g;X;t'U'm'u6z6z/u7g5|5N