rapid transit

(US) (system of) fast urban public transport, eg by underground or overhead railway 城市高速交通（系统）（如地铁或高架铁路）.

rang, range, range-finder, ranger, rani, rank, ranking officer, rankle, rankly, rankness, ransack, ransom, rant, ranter, rap, rapacious, rapaciously, rapacity, rape, rapid, rapid-fire, rapidity, rapidly, rapids, rapier, rapier-thrust, rapine, rapist, rapport, rapprochement, rapscallion, rapt, raptly, rapture, rapturous, rapturously, rare, rare earth, rarebit, rarefaction,