問題詳情:
The concept of maglev transportation was ______first presented in the mid-20th century and the first commercial maglev train line was put into ______ operation at Birmingham Airport in Britain in ㊣1984
A. the; the B. the; / C. /; the D. /; /
【回答】
D
知識點:冠詞
題型:選擇題