問題詳情
【題組】48. What helped to promote the spread of passenger elevators?
(A) The invention of steam-powered elevators.
(B) The introduction of safety elevators.
(C) The installation of electric elevators.
(D) The appearance of high-speed elevators.
參考答案
答案：B
難度：計算中-1
書單：沒有書單，新增