根据首字母及汉语提示，完成下列单词的拼写，使句意通顺。

小题1:Do you think this kind of water is s_____(安全) for drinking?

小题2:He is writing on the blackboard with a piece of c_____ (粉笔).

小题3:Our teachers are all very s_____ (严格) with us students.

小题4:Tom i_____ (邀请) all his best friends to his birthday party last Sunday.

小题5:We have to d_____ (携带) a lot of books in our school bags every day.

140平米的餐厅装修，轻钢龙骨吊顶上，纸面石膏板涂无机涂料的耐火等级（）

A.B3级

B.B2级

C.B1级

D.A级