Choose the best answer

When you are in Singapore, you can go around (17)                       taxi, by bus, or by underground. I myself prefer the underground (18)                                                    it is fast, easy and cheap. There are (19)____________  buses and taxis in Singapore and one cannot drive along the road (20) _______and without many stops, especially on Monday morning. The underground is therefore usually quicker than taxis or buses.                                                                                        

    17.     A. by           B. in                C. at               D. on

18   A. but                 B. because      C. when        D. so

19   .  A. little        B. a lot              C. many       D. any
20.   A. quick       B. quickly          C. quicker     D.quickest