副詞是一種用來修飾動詞,形容詞,全句的詞,說明時間,地點(diǎn),程度,方式等概念.副詞在句中可作狀語,表語,短語.

      careful是形容詞，修飾名詞。例如She is.a careful girl，她是個細(xì)心的女孩！carefully是副詞，修飾動詞。
      You should do the homework carefully.你要認(rèn)真做家庭作業(yè)。前者是形容詞,作定語或表語.如：He is a careful boy.He is careful.后者是副詞,作狀語,修飾動詞或整個句子.He reads the book carefully.