根据句意完成已给出首字母或汉语提示的单词，使补全后的句子意思通顺，语法正确。

S____  is the first day of a week.

It is p____  to keep your voice down in public.

Gina is a____ in class. She often answers questions.

—What's your favorite s____ besides maths, Sonia? —History.

Have you ever heard of the saying “ ____ （沉默）is gold”?

My friend Wang Ying comes from a____ （南方）town.

It's very____ （有帮助）to discuss your problems with your parents.

Our government has paid more attention to the problem about food ____ （安全）