问题 单项选择题

两种或两种以上组分混合时,不影响混合效果的是()

A.比例

B.密度

C.带电性

D.颜色

E.吸湿性

答案

参考答案:D

解析:本题考查的是组分的混合。影响混合效果的因素有:组分的比例、组分的密度、组分的带电性和吸附性、含液体或易吸湿性的组分、含可形成低共熔混合物。

单项选择题
单项选择题

Now which are the animals really to be pitied in captivity First, those clever beings whose lively urge for activity can find no outlet behind the bars of the cage. This is most conspicuous, even for the uninitiated, in the case of animals which, when living in a free state, are accustomed to roaming about widely. Owing to this frustrated desire, foxes and wolves housed, in many old-fashioned zoos, in cages which are far too small, are among the most pitiable of all caged animals.
Though pinioned swans generally seem happy, under proper care, by hatching and rearing their young without any trouble, at migration time things become different: they repeatedly swim to the lee side of the pond, in order to have the whole extent of its surface at their disposal, trying to take off. Again and again the grand preparations end in a pathetic flutter of their half wings ; a truly sorry picture !
This, however, rarely awakens the pity of the zoo visitor, least of all when such an originally highly intelligent and mentally alert animal has deteriorated, in confinement, into a crazy idiot, a very caricature of its former self. Sentimental old ladies, the fanatical sponsors of the societies for Prevention of Cruelty to Animals, have no compunction in keeping a grey parrot in a relatively small cage or even chained to a perch. Together with the large corvines, the parrots are probably the only birds which suffer from that state of mind, common to prisoners, namely, boredom.

What do you think "hatching and rearing their young" means

A. Raising families.
B. Getting on well with smaller birds.
C. Behaving like young birds.
D. Attacking smaller birds.