When she was in trouble, I did what I could to help her.my help, she wrote me a letter of thanks.

Your bedroom is so dirty. Would you please _______,Peter—OK, mum. I’ll do it right away.

Once harm is _______ to the eco-system, all species will ________, including man himself.

You made the same mistake for second time, dropping “n” in the word “environment”.

The policeman told the little boy ___football in the street. It’s dangerous.