Answer:

It's because they are afraid or scared that they accidentally speak something that is not in the worda that they must say.I also think that it's because of lack of confidence cause they think that as a begginer they have no experience and prone to doing mistakes while speaking.So they just lower their heads or look to the other way so they can avoid having eye to eye contacts from their listener or audience.

Explanation:

not sure if its 80 words but just add some words will yah

and also im not sure if my grammar is correct so please review it before writting thanks