题目

-- ______ shoes are these?-- They're _____ shoes. A . Whose; my B . Whose; hers C . Who's; our D . Whose; he 答案：A实验室制取二氧化碳气体时，最适宜的一组试剂是    [     ]A．纯碱( Na2CO3)与稀硫酸          B．碳和氧气  C．大理石和稀盐酸                D．石灰石和稀硫酸