动词、形容词重叠 Reduplication of verbs and adjectives

(1) 动词重叠 Reduplication of verbs
Reduplication of verbs is used to indicate that the action is either of very short duration or rarely taken. For the actions that have already taken place, “了” is inserted between the verb and its reduplication to express the short duration of the action. This structure is also used to make the tone of a sentence sound relaxed or informal, for example,
   邻居们也拍拍衣服准备回去。
   他看了看她说：“你瘦了。”
   他笑了笑，没有回答。
   我给他讲了讲这次旅游的情况。

If an action has not yet taken place or takes place frequently, the verb is often reduplicated to imply that the action is relaxed and informal, rather than being serious or done with effort, or that it is being done just for the purpose of trying something out. When used in connection with a request, command or wishes, reduplication of verbs can soften the tone of one's speech. For example,

    我的手机呢？你帮我找找吧。
    我马上就来，你让他去外边等一等。
    我想跟你随便谈谈。
    退休以后，他每天下下棋，跑跑步、练练书法、听听京剧什么的。


Note: This structure does not apply to actions in progress. Thus, it is in correct to say “我正在看看书” or “他们听一听音乐呢”. Verbs followed by “过”or “着”cannot be repeated either. It is incorrect to say “ 看看过” or “听听着”。

（2）形容词重叠 Reduplication of adjectives
When reduplicated, adjective often function ad adverbial modifiers or complements to indicate a higher degree. “地” is generally required after a reduplicated adjective as an adverbial modifier, for example,

   君子兰的叶子长得长长的。
   他轻轻地敲门。
   孩子高高兴兴地走了。
     when functioning as attributive modifiers or predicates, reduplicated forms of adjectives usually have a descriptive function, rather than emphasizing a high degree. When used as attributive modifiers, reduplicated adjective are usually followed by “ 的” ; When used as predicates, “的” is needed at the end of the sentence, for example,

    她高高的鼻子、大大的眼镜，漂亮极了。
    姑娘的头发长长的，个子高高的。
    书房里干干净净的。