With an appropriate relative pronoun:

(1)Do you know the reason ________ she has changed her mind?

(2)The woman ________ is talking to my mother is a friend of hers.

dynamic adjectives

tag question

extraposition

When the simple present refers to the present time,what are its characteristic uses?

restrictive adjectives

What's the function of relative pronoun?

Using a YES-NO question:

I don't know her telephone number.

Using an exclamation:

These old men are very nice people.

Using the passive voice:

We must put an end to this state of things as soon as possible.

Using subjunctive mood:

Why didn't you ask them to deliver your parcel?