通过以下反应均可制备:①煤炭与水反应制氢:②甲烷与水反应制氢:③太阳光催化分解水制氢:下列有关说法正确的是() A . 通过反应①可以将煤转化为清洁燃料 B . 若反应②使用催化剂,则减小 C . 反应③在低温下可以自发进行 D . 制备等物质的量的需要吸收的能量:①<②<③ 答案:AWhen he was 20, he left school and went to Beijing, ________he made great progress and becamean engineer.
[ ]A. what B. whichC. where D. when