Your friend is telling you the truth.为什么用ing形式?

is that your friend? Is this?your friend is For your friend is my friend是什么意思? Is this girl your friend?Is this your girl friend? is your my girl friend 英文什么 is your friend who is your best friend is your friend a girl? Is he your friend yes___. is anna your friend?回答 Is jim your friend?回答 Where is your friend feom? how,is,your,old,friend H什么 is your friend lined paper is your friend! 是Is Jim your friend or her friend还是Is Jim your friend and her friend Is she your friend,()? Yes,she is. is he your friend,为什么用is?