人教课标版 高二 必修5 Unit 5英语课件Heroic teenager receives awardUsing Language Let’s do some revision.Fill in the blanks.The skin is an _______ part of your body and it’s largest ______. You have _____ layers of skin which act as a barrier _______disease, _______ and the sun’s harmful rays. The _________ of your skin are also very _________: it keeps you _____ or cool; it prevents your body from ______ too much water;essentialorganthreeagainstpo..