Mathematically, mapping is a term that refers to the "corresponding" relationship between two groups of elements.

Question ②

no

That's for sure

and

only

Each element in set A has a unique element in set B..

The Q 3- 1 map shows that it is both injective and surjective.

Single shot means

Define two different elements in a domain.

Images mapped in the range must be different.

And surjective

This means that every element in an image set must have an original image.

The mapping can correspond to several elements.

And the one-to-one mapping is one-to-one.

It's hard.

as best as one can