题目

Singapore’s public transport system (公共交通系统) is one of the best in the world, so you should have no problem finding your way around like a local (当地人). There are three main forms of public transport that you would find in any other major city—trains, buses and taxis.TRAINSTrains run from 6 a.m. to midnight. Single trip tickets start at 80 cents. If you buy an EZ-Link card for $15, you can ride the trains and buses all you like.If you need more information, just call Transit Link on 1800 767 4333.BUSESThere are several bus services in Singapore and fares (车费) start at 神经纤维受到刺激时，刺激部位细胞膜内外的电位变化是（ ）①膜外由正电位变为负电位 ②膜内由负电位变为正电位 ③膜外由负电位变为正电位 ④膜内由正电位变为负电位A．①② B．③④ C．②③ D．①④