请肃静 vs. 请保持安静
Hi,

If I wanted to put up a sign at a library, for example, or anywhere else where I would like everyone to keep quiet, which would be better?

请肃静。

请保持安静。

Question

请肃静 vs. 请保持安静
Hi,

If I wanted to put up a sign at a library, for example, or anywhere else where I would like everyone to keep quiet, which would be better?

请肃静。

请保持安静。

Answer

The 2nd one, 肃静 is usually used in a very very official situation, like in court, or raising our national flag.
 请保持安静 means please be quiet, can be used in a library and in class/ meeting...

Answer

I would say use  "请保持安静", as it is more common in library or like you said anywhere else where you want to keep quiet

Answer

Jack nailed it. It's in the comments. Definitely go with "请保持安静" in your scenario.