After reading this article suggested by a friend, I feel more confused about the rules on how to use these words correctly.
I have some examples below:
- Pluto is a planet which revolves around the sun.
- Pluto is a planet that revolves around the sun.
Here's another pair:
- The book mentions some gardening tips which can be easily applied.
- The book mentions some gardening tips that can be easily applied.
One more:
- Every guy which arrives at the airport must pass a security check.
- Every guy that arrives at the airport must pass a security check.
Are there really some hard and fast rules like which one to use in every sentence like I mentioned above or are they interchangeable in above cases?