氢气是一种高能燃料,下列微粒中能保持氢气化学性质的最小粒子是[ ]
A.H
B.H+
C.H2
D.H2O
答案:C
Do you think that the bridge ______ in a year? [ ]
A. would be completed
B. will be completed
C. had been completed
D. is being completed
鉴别下列各组物质,所选试剂或方法错误的是[ ]
A.用燃烧法鉴别毛织品和化纤
B.观察法鉴别硫酸铜溶液和氯化铁溶液
C.用肥皂水区分硬水和软水
D.用酚酞鉴别氢氧化钠溶液和澄清石灰水溶液