Answer:
The first statement is incorrect.
The second statement is correct.
Step-by-step explanation:
1.C'est la troisième fois que je t'explique.
1.This is the third time that I explain to you.
Answer: it is supposed to be explained. With an "ed" at the end.
2. Cette petit fille est grand et gros.
2. This little girl is tall and fat.
Answer: this is a correct statement no wrong grammar.