one and a half years/apples?

[Daisylove88]

Dear teachers,
When I was in high school, I was taught that:
1, One and a half years is ...
2, a year and a half is...
2, One and a half apples is...
3, an apple and a half are...

It seemed to me that it is always "is" when it comes to time.

But some native English speakers told me otherwise: 1,are; 2,is; 3,are; 4,is.

So I'm now confused! please help！

[Mister Micawber]

.
The American Heritage Dictionary Usage note reads in part:

"Note that when followed by a fraction, 'one' ordinarily takes a plural verb: 'One and a half years have passed since I last saw her'. The fraction rule has an exception in that amounts are sometimes treated as singular entities: 'One and a half cups is enough sugar'. Note also that the plural rule does not apply to these 'one'-plus-a-fraction constructions that are introduced by the indefinite article. These are always singular: 'A year and a half has passed since I last saw her'."
_________________
Native English teacher at Mister Micawber's