当监视目标照度有变化时，应采用哪种镜头（）
A、电动聚焦镜头
B、自动光圈镜头
C、可变焦镜头
D、广角镜头
参考答案：B
小华在读一个小数时，把小数点读丢了，结果读成四万五千零一，原来的小数只读一个零，原来的小数是______，保留到十分位是______．
Directions: You will invite Professor Green to be the guest speaker at the NASHE 2007 annual conference (Beijing, China, 2007. 12.15-12.18). Write a letter of invitation to Professor Green.
You should write about 100 words on ANSWER SHEET 2. Do not sign your own name at the end of the letter. Use "Li Ming" instead. Do not write the address. (10 points)
