根据句意，写出划线单词的反义词

50.This room isn’t        .It’s very big.

51. Look at your hands! They aren’t        .They’re very dirty.

52. Don’t turn        .Turn right. Then you can find the post office on your right?

53. Give me that coat, please. That old one, not the        one.

54. That’s too noisy here. Please keep        , children.