Another: one other (singular)I have another question for you.The other : I have three teachers. Two of them are from Ribeirão and THE OTHER (teacher) is from Campinas.

Some of the students traveled last week and the other students/ones had to stay here.

(..) and the others had (...)

each other = one another (They hate each other= They hate one another) # They hate themselves.

Either.....or....... Neither.....nor..... Both.......and.......