between use only two person, things ,place and among More than two ......

what are you doing today?...

pronoun use in place of noun ...for exmpl...1 ram is a student, he(pronoun) is going to school.

my mother is housewife....

i am from Ludhiana

...on the earth

are you reached there....

4 part remove her

1first right because principles means... rule ,theory, idea ,concept and principal means.. chief main (( I'm sorry 1 sentence in " may in place of my is my " my mistake... sorry))

it's singular form.. piece of information, piece of bread ,piece of paper ......I think there are after Do not use " s / es "