学习本单元所掌握的重点知识
单词（四会要求）
Trolley bus, normally, quick, line, bridge, rather, public, narrow, advantage, advise, market, debate, engine, speed, bay, streetcar, connect, district, railway, trip, wise, include
短语：
1. advise sb. not to do sth.
2. enjoy our good public transit
3. old-time trolleys
4. travel up and down Market
5. the center of many of debates
6. the butt of many jokes.
