Choose

the right variant:

It means don’t go into the room or talk too loudly.

Choose the right variant:

It means don’t go into that place, usually a street. You are not allowed to go there.

Choose

the right variant:

We use it for a machine or service that is not working. 

Choose the right variant:

It means that something bad could happen and you need to be careful.

Choose

the right variant:

This

sign means