Quote Originally Posted by Antonio1986 View Post
I think I did a mistake: За последних пять дней.
Um, I'm most sure I'd say за последние пять дней and not за последних пять дней. But I think both variants are possible

As for examples:

The first 4 are okay

The 5th one should be:

Он будет учится четыре года.

Because it kind of fits in this statement

Quote Originally Posted by iCake
Нет предлога - Well, that's kind of tricky to explain this one. Well, it's usually used to say for how long the action is/was/will be active