观察图中有关操作和现象,判断下列叙述中正确的是
A.集气瓶中的气体可能是二氧化碳
B.集气瓶中的气体可能是空气
C.集气瓶中的气体一定是氧气
D.集气瓶中的气体一定是氮气
答案:A
下列各组中的化学式与俗名不一致的是( )
A.Ca(OH)2 消石灰
B.Fe2O3 赤铁矿
C.CaCO3 石灰石
D.CaO 熟石灰
What__________you yesterday? I saw you were talking with a boy angrily.[ ]
A. was happened to
B. happened with
C. happened
D. happened to