Dear Andy

I’m in London now. It’s the c  86  of England. I enjoy everything here except the food. I dislike English food. I miss dumplings and noodles.  Of course I never  s  87   missing you.

Things here are quite d  88  from those in China. T  89 in England goes on the left of the road. And if you want to go the other side of a road, you can have many ways: a subway(地铁), a footbridge or a zebra c  90  . And in some places, you can see black and white poles(杆). There is a button（键）on each of them. You can press the button to tell the drivers you want to cross the road. They usually stop their cars to let you go.

Taxis in London are really e  91  , so if you come to London, you should have enough m  92   with you. Taxi drivers are usually friendly. They are always ready to help you. And they must take exams b  93  they become taxi drivers.

London a   94   has the biggest underground system(系统) in the world. It’s easy to go the w  95   way if you are not careful.

Yours

Li Bing

金字塔是世界建筑史上的一大奇迹，要保证它不倒就需要把石条砌水平，古埃及人是如何做到的呢？有人猜想他们使用到了如图所示的工具--水平仪，该工具的物理原理是______________________________。生活中有时工人师傅也用根灌水的透明长塑料管检查水平，当管中的水静止时，当塑料管的一端提高5 cm，最终管两端水面的高度差为____________cm。