题目

When asked why he went there, he said he was sent there    for a space flight.  A.training             B.being trained      C.to have trained      D.to be trained   答案：D（2012?闸北区二模）实验室里不同化学试剂的保存方法不尽相同，①NaOH溶液、②大理石、③NaCl溶液、④稀硝酸4种试剂通常各自存放在如下图所示的玻璃试剂瓶中．按照试剂瓶的顺序存放试剂序号正确的是（　　）A．①②③④B．②①③④C．②③④①D．②①④③