下列系统中，( )是实时系统。

A．计算机激光照排系统

B．航空订票系统

C．办公自动化系统

D．计算机辅助设计系统

Directions:

There has been a discussion recently on the issue of challenge in a newspaper. Write an essay of 160-200 words based on the following drawing. In your essay, you should

1) describe the picture briefly.

2) explain the intended meaning, give a specific example, and

3) give your suggestion as to the best way to treat challenge.

You should write neatly on ANSWER SHEET 2.

挑战如同大风，可能是阻力，但是对于风车便是动力。