搜题请搜索小程序“爱下问搜题”
问题 推断题

已知某非金属单质A，在常温下很稳定，一定条件下A与氢气能化合成B，能使湿润的红色石蕊试纸变蓝色，B与氧气在一定条件下能生成C，C在空气中能自然氧化生成红棕色气体D，D溶于水生成E和C，E与B化合又生成F，F既是化肥也能用作炸药，A，B，C，D均为气体。

A，B，C，D，E，F的化学式分别为：A________B________C________D________E________F

答案

A：N2；B：NH3；C：NO；D：NO2；E：HNO3；F：NH4NO3

单项选择题

下列不是高效减水剂的外加剂是（）

A、萘系减水剂

B、蒽系减水剂

C、洗油系减水剂

D、聚羧酸系减水剂
查看答案
单项选择题

A study of adults who suffer from migraine headaches revealed that a significant proportion of the study participants suffer from a complex syndrome characterized by a set of three symptoms. Those who suffer from the syndrome experienced excessive anxiety during early childhood. As adolescents, these people began experiencing migraine headaches. As these people approached the age of 20, they also began to experience recurring bouts of depression. Since this pattern is invariant, always with excessive anxiety at its beginning, it follows that excessive anxiety in childhood is one of the causes of migraine headaches and depression in later life.
The reasoning in the argument is vulnerable to criticism on which one of the following grounds

A．It does not specify the proportion of those in the general population who suffer from thesyndrome.

B．It fails to rule out the possibility that all of the characteristic symptoms of the syndrome have a common cause.

C．It makes a generalization that is inconsistent with the evidence.

D．It fails to demonstrate that the people who participated in the study are representative of migraine sufferers.

E．(E) It does not establish why the study of migraine sufferers was restricted to adult participants.
查看答案