1. In English we know four demonstrative adjectives:

THIS ---------> Singular and close to the person speaking
THAT ---------> Singular and far from the person speaking
THESE --------->Plural and close to the person speaking
THOSE---------> Plural and far from the person speaking

2.On the other hand, Passive voice is a grammatical characteristic of sentences that we use to:

• Give emphasis to the object / action of the sentence.
• Talk about the description (origin, manufacture) of the object. In passive voice the subject of the sentence can be included using the preposition By. But this is not necessary:

3.My tea bags are made in India by Indian people

In passive voice sentences, we want to emphasize the object/action of the sentence because:

• Subject is obvious • Subject is not known
• Subject is not relevant to the information

4. Tea bags were first made of silk.
Those first tea bags we made by hand.
The first modern tea bags were manufactured in New York