2013高考英语一轮过关训练题：北师大版选修8Unit23（答案）
Ⅰ.完形填空
There have been many great inventions, things that changed the way we live.The first great invention was one that is still very important today－the wheel.This made it__1__to carry heavy things and to__2__long distances.
For hundreds of years after that there were few __3__that had as much effect as the__4__.Then in the early 1800’s the world started to change.There w
