"comma which", "that"

[MichaelZ337]

Dear Instructor

Whenever we see a "which clause" to modify a preceding noun, should there be a comma before which? If there is no comma before the "which clause", can we directly eliminate that choice? Is this rule 100% safe?

Whenever we see a "that clause" to modify a preceding noun, i understand that a comma cannot be placed before the that. Is this rule 100% rule safe?

thank you!

[RonPurewal]

Whenever we see a "which clause" to modify a preceding noun, should there be a comma before which? If there is no comma before the "which clause", can we directly eliminate that choice? Is this rule 100% safe?

in the standard u.s. english used on this test, yes, there should be a comma. they won't write a correct answer without a comma in front of which.

on the other hand, they probably won't write any wrong answers in that way, either. i can't imagine that this will be an issue either way.

note that this principle does NOT apply to "of which", "in which", "from which", and so on. those can be used either with or without commas.

[RonPurewal]

Whenever we see a "that clause" to modify a preceding noun, i understand that a comma cannot be placed before the that. Is this rule 100% rule safe?

if you use this principle blindly--i.e., without considering the context--then, no, not "safe". you can have a comma there, if it belongs to a different construction.

e.g.,

In the ceiling of my bathroom, there is a sprinkler, intended to spray only in the event of a fire, that sometimes sprays for no reason.

In the ceiling of my bathroom, there is a sprinkler that, on at least two occasions, has sprayed for no reason.

[RonPurewal]

^^ in both of those examples, the "base sentence" (black letters) doesn't contain any commas. the purple-colored modifiers, on the other hand, do have commas--and those commas will go wherever the modifiers go.

[MichaelZ337]

Great thanks, Ron!

[RonPurewal]

you're welcome.