Question

Scientists found a great way to use flowers for cars. The oil from some flowers can make cars run. 1) It needs a special engine. 2) It uses flower oil to run cars. 3) This is a great way to save money. 4) It also makes the air clean. Now flowers can be useful in many ways.

(What does each number refer to?)
1) It---
2) It---
3) This ---
4) It---

Answer 1

This is interesting -- having you think about antecedents for rather vague pronouns!!

1. It = flower oil

2. It -- no particular antecedent that I can see

3. This = the act of using flower oil to run cars

4. It = the act of using flower oil to run cars