经纪人在洽谈签约艺人的戏剧演出活动，一般情况下效益考量点中首要考量的是（） A.导演

纳税人与税务机关在有关纳税方面发生争议时，必须先履行纳税义务才能提出行政复议。（）

与能量代谢有关的是（）

A．叶酸

B．维生素B₁

C．维生素A

D．维生素C

E．生物素

累计投标询价及配售完成后，发行人及其保荐机构应刊登配售结果公告。配售结果公告至少应包括( )。

A．累计投标询价情况，包括：所有询价对象在不同价位的有效申购数量，不同价位以上的累计有效申购数量及其对应的超额认购倍数

B．申购总量和冻结资金总额

C．发行价格以上的有效申购获得配售的比例及超额认购倍数

D．获得配售的询价对象名单、获配数量和退款金额

E．发行价格以下的有效申购获得配售的比例及超额认购倍数

All animals must rest, but do they really sleep as we know it The answer to this question seems obvious. If an animal regularly stops its activities and stays quiet and unmoving—if it looks as though it is sleeping—then why not simply assume that it is in fact sleeping But how can observers be sure that an animal is sleeping

They can watch the animal and notice whether its eyes are open or closed, whether it is active or lying quietly, and whether it responds to light or sound. These factors are important clues, but they often are not enough. Horses and cows, for example, rarely close their eyes, and fish and snakes cannot close them. Yet this does not necessarily mean that they do not sleep. Have you ever seen a cat dozing with an eye partly open Even humans have occasionally been observed to sleep with one or both eyes partially open. Animals do not necessarily lie down to sleep either. Elephants, for example, often sleep standing up, with their tusks resting in the fork of a tree. Finally, while "sleeping" animals often seem unaware of changes in the sounds and light and other stimuli around them, that does not really prove they are sleeping either.

Observations of animal behavior alone cannot fully answer the question of whether or not animals sleep. The answers come from doing experiments in "sleep laboratories" using a machine called the electroencephalograph (EEC). The machine is connected to animals and measures their brain signals, breathing, heartbeat, and muscle activity. The measurements are different when the animals appear to be sleeping than when they appear to be awake. Using the EEC, scientists have confirmed that all birds and mammals studied in laboratories do sleep. There is some evidence that reptiles, such as snakes and turtles, do not truly sleep, although they do have periods of rest each day, in which they are quiet and unmoving. They also have discovered that some animals, like chimpanzees, cats, and moles (who live underground), are good sleepers while others, like sheep, goats, and donkeys, are poor sleepers. Interestingly, the good sleepers are nearly all hunters with resting places that are safe from their enemies. Nearly all the poor sleepers are animals hunted by other animals: they must always be watching for enemies, even when they are resting.

According to the research findings mentioned in the passage, reptiles（）

A. such as turtles and snakes cannot close their eyes

B. cannot be studied with an EEC

C. do not sleep in the true sense of the word

D. do not need to rest

下列选项中属于蒸发目的的是（）

A、排出多余水份

B、将种分母液蒸浓

C、排出Na₂CO₃

D、给电厂送软化水