从高锰酸钾制取氧气之后的残渣中回收纯净、干燥的二氧化锰,其步骤有:①过滤②烘干 ③溶解 ④洗涤,正确的操作顺序是( )
A.③①④②
B.③②①④
C.③①②④
D.①②③④
答案:A
—Would you like to climb mountains with me this Sunday?
—I'd love to. But I _______ play table tennis between Class Three and our class.[ ]
A. am going
B. am going to
C. am
D. going to
顾客满意是指哪几方面的内容?