Answer:
snows, freeze
Explanation:
Every time it <u>snows</u>, our water pipes <u>freeze</u>.
-> The last one does not make sense (it are snowing, pipes is freezing)
-> The second one is a bit better, but "are freezing" is present tense, while is snowing is also present tense, the sentence itself is talking about the past, hence why "snows" fits better
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather
