【英语时差8,16】手为什么会颤抖？

 Hold your hand out and try to keep it perfectly¹ still. After a moment, it will probably begin to shake. Hold that same hand out just before you give a major presentation to your new boss, and you’ll notice that those normal small tremors² increase substantially. Why? The answer has to do with how nervous feelings influence a response cycle between two parts of your brain. These parts are called the basal ganglia and the cortex. In order for your brain to control the steadiness of your hand, the cortex and the basal ganglia exchange signals with each other. First, the cortex sends a signal to the basal ganglia; the basal ganglia, in turn, responds returning a signal to the cortex. These signals are the basis of motor control. By exchanging signals, the cortex and the basal ganglia allow your hand muscles to hold their position. This cycle of signals repeats continuously the entire time your hand is extended³.

1 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

2 tremors   

震颤( tremor的名词复数 )； 战栗； 震颤声； 大地的轻微震动

参考例句：

• The story was so terrible that It'sent tremors down my spine. 这故事太可怕，它使我不寒而栗。
• The story was so terrible that it sent tremors down my spine. 这故事太可怕，它使我不寒而栗。

3 extended   

adj.延伸的；伸展的；延长的；扩大的v.延伸(extend的过去式和过去分词)；伸展；延长

参考例句：

• an extended lunch hour 延长了的午餐时间
• France has greatly extended its influence in world affairs. 在世界事务中，法国的影响已大大地扩大了。 来自《简明英汉词典》