1．人脑的重要性及作用。
2．如何科学用脑。
写作导航：先写大脑的特性和作用(复杂、智能的器官，使人区别于动物等)；再写大脑越用越灵，但过度使用也会出问题，为第三段作铺垫；第三段从两方面说明如何合理用脑：一是劳逸结合，手脑交替；二是从科学的角度，利用数据，说明过度用脑可能给大脑带来的伤害。
范文：
Human brain i the mot complex and intelligent mechanim in the world. It i the major factor that ditinguihe man from animal. With our brain we get to know the world and make a good ue of the world to our benefit.
Our brain i a product of contant ue through million of year. Other thing can be ued up, but ued properly, our brain can never be exhauted. In fact, the more we ue it, the more capable and efficient it will become. Exceive ue of the brain, however, will cauea lot of problem. So it i ueful to know how to ue our brain wiely.
Firt, handwork or phyical labor i good exercie a well a ret for our brain. Doing handwork and brain work alternatively can help develop both our brain and hand. Secondly, we hould avoid doing brainwork for long hour on end. The brain, though 3% of the body weight, when at work, conume 20% of the oxygen carried by 16% of the blood in circulation. A long period of brainwork may caue, through lack of bodily activity, low blood circulation and inadequate oxygen upply to the brain, reulting in inefficiency and poible damage to the brain.(英语作文)[由wwW.HaoZuoWen.com整理]