To express prediction, expectation and assumption, the following auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") are used.

You should be on time.
We ought to protect the environment.

In writing, should can also be used to express a strong obligation politely:

Guests should vacate their rooms by midday.

To express past criticism the same auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") are used as in the case of present criticism. However, the infinitives that follow are perfectThe aspect expressing completion. E.g.: He’s finished university. infinitives.

To advise someone what they should do, the following auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") can be used.

You should smoke less.
You had better leave.
You ought not to open that box, Pandora. (or: You oughtn't to open that box.)

Note that ought to is rather formalNot belonging to colloquial or everyday speech; official. E.g.: I demand that Mr Smith call the person on whom the committee has decided..