身材矮小，但比例均称的疾病是（） A.营养不良 B.生殖腺功能不全 C.克汀病 D.

地球上的植物多姿多彩，人们难以找到两片完全相同叶片，这一现象体现了[ ]

A．物种的多样性

B．生态系统的多样性

C．遗传的多样性

D．环境的多样性

能通过化合反应得到的是（　　）

①FeCl₂   ②H₂SO₄   ③NH₄NO₃   ④HCl    ⑤Cu₂S  ⑥Fe（OH）₃．

A．仅②③④⑥

B．仅②③④⑤⑥

C．仅①②③④

D．全部

阅读理解。

     Studying for an exam while listening to music is not smart, because background music can injure

your ability to perform memory tasks, new research has found.

     Study participants were asked to recall a list of eight consonants (辅音字母) in the order they

were presented. They did this while in five different sound environments: quiet surroundings; music

they liked music they disliked; changing state; and steady state.

     The participants recall ability was poorest when listening to music, regardless of whether

they liked or disliked it, and in changing-state conditions. The most accurate recall occurred

     when participants performed the task in steady-state environments, according to the study

published online in the journal Applied Cognitive Psychology.

     The poorer performance of the music and changing-state sounds are due to the audible (听得

见的) change within those environments. This hurts the ability to recall the order of items, via retelling,

within the presented list, explained lead researcher Nick Perham, a lecturer in the School of Psychology

at the University of Wales Institute in Cardiff, in a news release from the journal's publisher.

      "Mental arithmetic (算术) also requires the ability to memorize order information in the short-term

via retelling, and may be similarly affected by their performance in the presence of changing-state,

background environments," he added.

1 When performing a challenging mental task, you'd better do it ______.

A. in the music you like                

B. in the music you dislike

C. in changing state                    

D. in steady state

2. The reason why the participants performed poorly while listening to music is that ______.

A. the music was too loud

B. they got lost in the music

C. the changeable sound disturb the input of the information

D. they couldn't focus their attention

3. Which of the following is in steady state?

A. 12345.        

B. 33333.

C. abcde.          

D. a1b2c.

4. We can learn from the text that ______.

A. When doing our homework, we'd better play sweet songs

B. Music may affect our performance of memorizing

C. Mental arithmetic means retelling the order of information

D. Reading in the noisy street can strengthen our ability of concentrating

下列企业中，不得享受生产性外商投资企业税收优惠待遇的是( )。

A．专业从事机械制造、电子工业的外商投资企业

B．专业从事房地产开发经营的外商投资企业

C．从事直接为生产服务的科技开发的外商投资企业

D．从事农业的外商投资企业

高温堆肥的堆制腐熟过程可分为（）、（）、（）和后熟保肥四个阶段。