- As light pollution increases , seeing the stars will be harder
- A telescope is used for observing stars
- Therefore, as light pollution increases, using telescope to see the stars will be harder

- As light pollution increases, using telescope to see the stars will be harder
- As distance to a city decreases , the amount of light pollution will increase
- So, as distance to a city decreases, the increased light pollution will make using telescope to see stars harder

- The statement "Centimeter is usually used to measure short length " is irrelevant

Therefore, as distance to a city decreases, the increased light pollution will make using telescope to see stars harder
Q: Why are many telescopes used far from cities?
Context:
- As distance to a city decreases , the amount of light pollution will increase 
- As light pollution increases , seeing the stars will be harder 
- A telescope is used for observing stars
- Centimeter is usually used to measure short length 