关于十二指肠的描述，不正确的是（）。 A.肌层分为内环、外纵两层 B.上皮为单层柱状

阅读理解。

     David and his brother Grey don't go to school in the morning. They go to school after lunch, at one

o'clock. They have math at one-fifteen, David likes math because it's interesting. Greg doesn't like math.

David and Greg have P.E. after math. They like the teacher, Mr. Green and they like P.E. because it's

fun. But Greg's favorite subject is art and David's favorite is music. He plays the piano and the violin.

根据短文内容判断正（T）或误（F）。

( )1. David and Greg have P.E. after math.

( )2. David plays the piano.

(     )3. They go to school in the morning.

(     )4. They don't like P.E. because it's boring.

(     )5. Grey likes his art class.

简述谷疸的病因、病机、主证和治法。

下列建设工程招标投标行为中，属于投标人不正当竞争行为的有（）。

A.招标人相互串通投标 

B.投标人与招标人串通投标 

C.招标人操纵中标 

D.投标人以他人名义投标 

E.投标人以高于市场定价的报价竞标

下列说法均是错误的，请各用一个化学方程式来证明它的错误：

（1）分解反应前后元素的化合价一定改变                                              ，

（2）有盐和水生成的反应一定是中和反应                                             。