Question

I had been reading this book for two weeks before a= she had arrived b= she arrived c= she has arrived.

Answer 1

I had been reading this book for two weeks before she had arrived.

Explanation:

• Has, have, has, are helping verbs that are added before a noun.

• Have is used for the pronouns and plural nouns.

• Whereas Has is used for the third singular person.

• Had is used in the past tense to show the completeness of action.  

• Been is added with the three of them i.e. has, had, have, to show the continuity of action.