that when you exercise,your body produces
some chemicals that make you feel peaceful and relaxed and increase your ability to
concentrate when you study
1.它是主系表結(jié)構(gòu).
2.具體分析如下：
主語：Many teenagers
系動詞：are
表語：surprised
(原因)狀語：to learn that when you exercise,your body produces
some chemicals that make you feel peaceful and relaxed and increase your ability to concentrate when you study.
注：此句用不定式做原因狀語,再如：
I'm sorry to hear the news.
3.做原因狀語的不定式中的learn后面是一個以that作為引導(dǎo)詞的賓語從句.
該賓語從句結(jié)構(gòu)分析如下：
when you exercise為賓語從句中的時間狀語從句（其中的you和exercise分別為時間狀語從句的主語和謂語）；
your body為主語；
produces為謂語；
some chemicals為賓語；
其后的that make you feel peaceful and relaxed and increase your ability to concentrate when you study為定語從句,修飾chemcals做定語.
4.該定語從句分析如下：
1）that即是定語從句的關(guān)系代詞/引導(dǎo)詞,又在定語從句中充當(dāng)主語,相當(dāng)于先行詞chemicals；
2）make為謂語；
3）you為賓語；
4）feel peaceful and relaxed以及increase your ability to concentrate為用and并列的兩個賓語補足語；
其中to concentrate為不定式做后置定語,修飾ability；
5）when you study為時間狀語從句,其中you和study為主語/謂語.