时差N小时 风力发电机(下)

Turbines with one or two blades are actually even more efficient. But because they’re also lighter¹ and tend to spin faster, they’re also noisier. These designs also require a special tilting² hub that acts as a sort of shock absorber, which is expensive. On the other hand, having more than three blades raises other problems. For one thing, the extra material needed to build the blades raises the cost. And the more blades there are, the lighter and thinner they need to be. Relatively³ thin blades are more flexible, making them prone⁴ to bend and break. Three-bladed turbines aren’t perfect, but they avoid many of these problems. They’re powerful enough without being overly expensive. And they’re less noisy than their two bladed cousins.

带一个或两个叶片的涡轮机实际上更有效率。但是因为这样重量较轻，旋转速度更快，噪音也就更大。设计还需要一个特殊的作为一种减震器的倾斜轮轴，它很贵。另一方面，如果叶片超过三个也会引发其他问题。一方面，建造更多的叶片需要更多的材料，这提高了成本。而且叶片，叶片就要更轻，更薄。很薄的叶片也更灵活，但容易弯曲和断裂。三个叶片的涡轮机并不完美，但会避免这些问题。他们造价不高，但是功率足够了。而且两个叶片的涡轮机噪音小。

1 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

2 tilting   

倾斜，倾卸

参考例句：

• For some reason he thinks everyone is out to get him, but he's really just tilting at windmills. 不知为什么他觉得每个人都想害他，但其实他不过是在庸人自扰。
• So let us stop bickering within our ranks.Stop tilting at windmills. 所以，让我们结束内部间的争吵吧！再也不要去做同风车作战的蠢事了。

3 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

4 prone   

adj.(to)易于…的，很可能…的；俯卧的

参考例句：

• Some people are prone to jump to hasty conclusions.有些人往往作出轻率的结论。
• He is prone to lose his temper when people disagree with him.人家一不同意他的意见,他就发脾气。