单选题 —I always look out before crossing the street.
—You are right. You can't be too______.

【正确答案】 B

【答案解析】[参考译文] ——我在过街前总是要留神四处看一下。——你这样做是正确的，要尽可能小心。短语can't be too careful意思是as careful as possible“尽可能小心”。