Are these nouns concrete or abstract cup elephant gasoline abstract?

Here's the breakdown of the nouns and whether they are concrete or abstract:

* Cup: Concrete (You can touch and see a cup)

* Elephant: Concrete (You can touch and see an elephant)

* Gasoline: Concrete (You can touch and see gasoline, although it's not a solid)

* Abstract: Abstract (This is a concept, not a physical thing)

Let me know if you have any more words you'd like to classify!