A set of books giving information on many subjects.

Encyclopedia = a book or set of books giving informations on many subjects or on many aspects of one subject and typically arranged alphabetically.

would is used for past and will is used in present tenses.

A piece of jewellery that hangs from a chain worn round the neck

could is past tense of can and would is past tense of will

because in the sentence there is I which is in present tense as plural so have had been returned. It had took been because of present perfect tense used in sentence. Been is a form of be that is used in perfect tense.

the upward option is correct but there is one more reason that is that we use have rather than has because I is plural in present tenses

the is a artical same as a and an.

wake up or get up.