Seeing someone yawn, or even the thought of it, can make you yawn too.
The answer is A. prepositional phrase
Answer:
Sentential form
Explanation:
A sentence is a sentential form when it has only symbols (P, Q, A...). It may have terminal symbols or start symbol.
The word harbingers as it is used in this excerpt is a person or thing that announces or signals the approach of another.