Что поставить? it's a/an blue school bag. betty are/is 14 years old. mark and ann are/is in the same science class. the eraser/erasers are in her pencil case. this is an/a orange. john 'm/'s new to the school

It's a blue school bag.
Betty is 14 years old.
Mark and Ann are in the same Science class.
The erasers are in her pencil case.
This is an orange.
John's new to the school.

Betty is Mark and Ann are The erasers are This is an orange Jon"s new