托福閱讀高難度文章長(zhǎng)難句實(shí)例解析：打哈欠的科學(xué)原理和作用

　　According to conventional theory, yawning takes place when people are bored or sleepy and serves the function of increasing alertness by reversing, through deeper breathing, the drop in blood oxygen levels that are caused by the shallow breathing that accompanies lack of sleep or boredom.

　　詞匯講解：

　　conventional /k?n'v?n??nl/ adj. 傳統(tǒng)的;老套的，千篇一律的;約定的

　　alertness /?'l?:tnis/ n. 警戒，機(jī)敏

　　reverse /r?'v??s/ v. 使(某物)反轉(zhuǎn); 將(某物)翻轉(zhuǎn);轉(zhuǎn)變

　　結(jié)構(gòu)劃分：

　　(According to conventional theory), yawning takes place (when people are bored or sleepy)and serves the function (of increasing alertness) (by reversing, through deeper breathing, the drop in blood oxygen levels) (that are caused by the shallow breathing) (that accompanies lack of sleep or boredom).

　　深度分析：

　　這個(gè)句子的主干就是：

　　yawning takes place and serves the function

　　修飾一：(According to conventional theory)，介詞短語

　　中文：根據(jù)傳統(tǒng)理論

　　修飾二：(when people are bored or sleepy)，從句

　　中文：當(dāng)人們感到厭煩或困倦時(shí)

　　修飾三：(of increasing alertness)，介詞短語

　　中文：增強(qiáng)警覺

　　修飾四：(through deeper breathing)，插入語

　　中文：通過深呼吸

　　修飾五：(by reversing, through deeper breathing, the drop inblood oxygen levels)，介詞短語，注意這里修飾四的插入語隔開了，斷句別出錯(cuò)

　　中文：通過淺呼吸逆轉(zhuǎn)血液中氧含量的下降

　　修飾六：(that are caused by the shallow breathing)，從句，修飾the drop in blood oxygen levels

　　中文：是通過淺呼吸導(dǎo)致的

　　修飾七：(that accompanies lack of sleep or boredom)，從句修飾，theshallow breathing

　　中文：伴隨著缺乏睡眠或厭煩

　　參考翻譯：

　　根據(jù)傳統(tǒng)理論，打哈欠會(huì)在當(dāng)人們感到厭煩或困倦時(shí)發(fā)生，并且打哈欠通過深呼吸逆轉(zhuǎn)血液中氧含量的下降(這種下降是由伴隨著缺乏睡眠或厭煩的淺呼吸造成的)起到提升警覺的作用。