A:锂是较轻的金属
B:LiOH的碱性比NaOH弱
C:锂的化学性质比钠活泼
D:锂在空气中燃烧生成Li2O
重组单词
① It's ____ the library.
② What a great ____!
③ ____ is the post office?
④ The shop is ____ to the door.
⑤ Today is Tuesday. We have ____.
下列具有保护功能并属于上皮组织的是( )