A man and a woman are talking on the phone:
I'm sorry, but can you please cancel my appointment for today?
Sure thing.
Is there another day when you can come in?
How about Saturday? The morning is better for me.
What is the difference between the two sentences?
1-) Is there another day when you can come in ?
2-) Is there another day that you can come in?
Best Answer
A native speaker could use either of those sentences. "Is there another day when you can come in?" has better grammar. In fact, the other one is bad grammar, but it's commonly used by native speakers.
Sentence 1: A relative clause with "when" describes a noun by using that noun in an adverbial of time. In this case, the deeper structure of the sentence is:
The pronoun "when" replaces the adverbial "on that day". "Day" refers to the same "day" as earlier in the sentence.
Sentence 2: A relative clause with "that" describes a noun by using it as a subject or an object in another sentence. The grammar doesn't work here, because "You can come in" already has a subject, "you", and there's no place for an object. The word "in" is part of the phrasal verb "come in", not a preposition, so it cannot take an object. "...that you can come in" suggests a deeper structure like:
which is nonsense. One way to fix this is to add the preposition "on" to the end:
You can come in on a day, so this is good grammar.