Only used with other related pronouns.

Answer D This is the attributive clause library, which is the antecedent, followed by the place where we often read.

Come on! !

This question is about locative adverbial clauses and modifier libraries. If you use which, you should put the preposition in before it. Before that, you can't add prepositions, you can only fill in adverbs where. If you use that, you will read it carefully and it will become an emphasized sentence pattern. If you emphasize the sentence patterns here, it should be that I found Mr. Smith in the library. Obviously, what follows is the adverbial clause of place which is oriented to where to modify the library.

Option d

Keep the sentences coherent and ask, "where did you find Mr. Smith?"

A emphasizes that "we often go to the library" means "Mr. Smith and I often go to the library for management, not anywhere else"

C is the attributive clause "in the library (where we often go) (where we found him)"

Which sentence is wrong? It should be "This is the library we have been to." You can also say, "This is the library we have been to." As an attributive clause. (Note that these three sentences are attributive clauses, which are in the place where we went to the library, not adverbial clauses.

You'd better make a mark where there is a problem.

You'd better make a mark where there is a problem.

The above two words have the same meaning, except that the first is an adverbial clause and the last is an attributive clause. The attributive clause has the position of antecedent, but the adverbial clause does not. The Where-guided sentence in the adverbial clause is an adverbial of place, and there is no place.

The antecedent location appears in the attributive clause, and then the location is modified with the attribute guided by where.

That's in the library where we often read.