1-2) may (asking permission)
3-4) can (asking permission)
5-6) could making request)
7-8) should giving advice)
9-10) must (command)
11-12) can (denoting a factor ability
13-14) could (denoting a fact
15-16) may (denoting possibility)
17-18) cant (denoting something that cannot be done)
19-20) shouldnt (phohibition or phohibiting someone to do​