Hebrew has a word, asher (accent on the second syllable, so ah-Sher), loosely translated at the back of a Hebrew grammar I have, as “that, which, who,” a woefully oversimplified definition of this complex word, but it fits perfectly as the title of today’s lesson. These three words are easy to get wrong in English. But when you get these three words right, you improve your writing.
You can use that in a whole bunch of ways. Mainly it’s a relative pronoun. It shows some connection between two things. Use it when the connection is important to the sentence. Do not use “which.”
Here is the motorcycle that my brother rides.
That is also a demonstrative: That man is riding a motorcycle. I remember my English teacher used to demonstrate multiple uses of “that” with this sentence:
That “that” that that man said was wrong.
The first and last are demonstratives, the third one is relative, and the one in quotes is a noun.
Use which when the connection is not important to the structure of the sentence—when you have an aside. It is usually right after a comma.
Correct: Bob’s motorcycle, which is the black one, is a Harley.
Incorrect: Here is the motorcycle which my brother rides.
A lot of people use which when that will do, and I’ll probably never win this battle, but still, don’t. It’s pretentious.
Use who when you refer to people; use that when you refer to things.
Correct: The tough-looking guy who just climbed onto his motorcycle is my brother.
Incorrect: The tough-looking guy that just climbed onto his motorcycle is my brother.
There you have it. In case you are wondering, my brother really does ride, and his bike is a Harley. Here he is, taking my wife for a ride.