下列关于钠的叙述中,不正确的是[ ]
A.钠燃烧时发出黄色的火焰
B.钠燃烧时生成氧化钠
C.钠有很强的还原性
D.钠原子的最外层只有一个电子
答案:B
You__________the parcel home. The shop would have delivered it if you had asked.
A.needn’t have carried
B.couldn’t have carried
C.mustn’t have carried
D.shouldn’t have carried
下列哪个征象不是亚急性甲状腺炎的常见表现()
A.甲状腺吸131Ⅰ率降低
B.血清甲状腺激素增高
C.血沉升高
D.过氯酸盐释放试验异常
E.颈部疼痛