I have a question, do we have to add ‘to’ after forbidden? For example: <ol> <li>In the hospital is forbidden make noise</li> <li>In the ...

Good question Mildred! The second one is better, although here are some more corrections:

In the hospital, it is forbidden to make noise.

Hello. Answering your question, yep, you need to place "to" after forbidden. The reason is that in the example you have there are two verbs together. Forbid and Make. So, to place two verbs together we have some options like using "TO" or "ING". That's the reason. . I hope my answer has helped somehow.

Pets are forbidden at hospitals