在规定的暴露条件下，某种化学物质引起机体产生有害变化的最低剂量或浓度

在规定的暴露条件下，未观察到某种化学物质引起机体产生有害作用的最高剂量或浓度

毒物引起一组受试实验动物半数死亡的剂量或浓度

某种物质使机体产生效应的最低剂量或暴露浓度

为保护人群健康，对环境及各种环境介质中与人群健康有关的各种因素所规定的浓度和暴露时间的限制量

attention

need

satisfaction

visualization

action

NOEL

LOAEL

NOAEL

MED

情感高涨

情感低落

恐惧

焦虑

primary

secondary

nontechnical

semitechnical

11：Reading Comprehension Today TV audiences all over the world are accustomed to the sight of American astronauts in tip-top condition, with fair hair, crew-cuts, good teeth, an uncomplicated sense of humour and a severely limited non-technical vocabulary. What marks out an astronaut from his earthbound fellow human beings is something of a difficult problem. Should you wish to interview him, you must apply beforehand, and you must be prepared for a longish wait, even if your application meets with success. It is, in any case, out of the question to interview an astronaut about his family life or personal activities, because all the astronauts have con- tracts with an American magazine under conditions forbidding any unauthorized disclosures about their private lives. Certain obvious qualities are needed. Any would be spaceman must be in perfect health, must have powers of concentration ( since work inside a spacecraft is exceptionally demanding) and must have considerable courage. Again, space-work calls for dedication. Courage and dedication are particularly essential. In the well-known case of the Challenger seven crew members lost their lives in space because of the faulty equipment in the shuttle. Another must is outstanding scientific expertise. It goes without saying that they all have to have professional aeronautical qualifications and experience. A striking feature of the astronauts is their ages. For the younger man, in his twenties, say, space is out. Only one of the fifty men working for NASA in 1970 was under 30. The oldest astronaut to date is Alan Shepard, America's first man in space, who, at nearly fifty, was also the man who captained Apollo 13. The average age is the late thirties. The crew members of Apollo 11 were all born well before the Second World War. In 1986 the Challenger astronauts had an average age of 39. The range was from 35 to 46. In a society where marital continuity is not always exhibited, the astronauts' record in this respect hits you in the eye. Of all the married men in NASA group, only two or three are divorced from their wives. Mind you, it is hard to tell whether something in the basic character of an astronaut encourages fidelity or whether the selection process demands that a candidate should be happily married. The NASA astronauts live in unattractive small communities dotted here and there around the base in Texas. You would expect them to find their friends from among their professional associates, but this is not the case. Rather, they prefer to make friends with the normal folk in their districts, A good job, too, Astronauts, like everybody else, must get fed up with talking shop all the time, and, whereas they are indeed an elite, their daily life outside work should be as normal as possible, if only for the sake of their families. As for the astronauts' political leanings, they seem to be towards the right. This may be due to the fact that a large proportion of the astronauts have a military background. On the other hand, it could be just coincidence. In politics, astronauts are generally A.democrats.

republicans.

conservatives.

communists.

焦虑

恐惧

欣快感

情感低落

7，3，4，6

7，2，3，4

7，2，4，5

7，3，4，5

正确

错误