题目

— Oh no! We're too late. The train ________. — That's OK. We'll catch the next train to London. A. was leaving                          B. had left C. has left                             D. has been leaving 答案：C 句意：——噢不！我们太晚了。火车已经离开了。——没什么。我们将乘下一列去伦敦的火车。根据语境可知火车已经离去，故用现在完成时。下列物质的用途跟其化学性质相关的是（　　） A、干冰用于人工降雨B、氧气用于急救病人C、稀有气体用来制作电光源D、铜用作电线