题目

同温同压下，1体积X2气体与3体积Y2气体化合生成2体积气体化合物，则该化合物的化学式为                 （    ） A.XY              B.XY3               C.X3Y             D.X2Y3 答案：B263. --- When will that opera be ______?--- I don’t know. But I hope they can _____ next Sunday.put on; put on it            B. put on; put it on        C. put off; put off it             D. put in; put it in