题干

下列说法正确的是(   )

A:液态HCl、固体NaCl均不导电,所以HCl、NaCl均不是电解质

B:SO2的水溶液能导电,所以SO2是电解质

C:蔗糖、酒精在水溶液里和熔融状态时均不导电,所以他们不是电解质

D:铜、石墨均导电,所以它们是电解质

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答案(点此获取答案解析)

C

同类题1

阅读《最小的星星也闪光》 ,回答相关问题
①潘小锋是个寡言少语、性格内向的学生,瘦削的脸上有着一双透着忧郁却又叛逆的眼睛。他总是喜欢一个人躲着看他的动漫书,偶尔也会在纸上涂鸦着什么,平时很少参与班集体的活动,与班上的其他同学也极少来往,似乎成了被人遗忘的人。
②那天,我正在神采飞扬地讲着课,学生都安静地听着。突然,原本安静的教室却被一声窃笑搅起了层层波浪。我怒火中烧循声望去,发现是潘小锋的同桌张晓琴在笑。张晓琴发觉我盯着她,不好意思地低下了头。
③我铁青着脸说:“张晓琴,你笑什么?”
④张晓琴立马站起来小声说:“老师,他在画你——”并用手指着潘小锋课桌上的纸。
⑤一下子,全班的目光齐刷刷地锁定在我和他的身上,旁边的几个学生猫着身子偷看他的画,也都偷笑起来。我一个箭步过去,一把抢过他的画,圆睁着愤怒的双眼,看着他在画我上课的样子,真是气不打一处来!
⑥“潘小锋,你给我站到墙角去!”我用强硬的命令口吻叫嚷着。他耷拉着脑袋晃悠悠地走了过去。“上课不听开小差也就算了,竟敢丑化老师,岂有此理!明天叫你家长来。”他仍然低头不语,脸一下子红到了脖子。那堂课是我与他头一回交锋,也是他进入我视线的开始。
⑦放学后,拿着缴来的画来到办公室,教师应有的品行规范让我平静下来。细细端详他的画,觉得倒十分形象,有几分趣味,心情也渐渐舒展开来。
⑧第二天,我在办公室静等他和他家长的到来,可是一个上午都没见人影。后来得知他因害怕告诉他父亲实情而挨打,一个人躲进了网吧。知道这一切后我和他父亲一起在一家网吧中找到了他,并把他带回了家。
⑨到他家天色已晚了,天边零星地冒出几颗闪着光亮的星星。他父亲把我让进家门,招呼我:“老师辛苦了!坐一坐,家里太小太乱,不好意思。”我笑笑便坐了下来,环视了一下房间。这是一间不到30平方米的低矮房,墙壁灰暗,摇摆的蛛丝零落地挂在屋角,一些旧式家具零乱地堆放在各处,上面随意堆放着一些图书报刊,看来已许久没整理过了。
⑩“老师别生气,您喝茶!”我接过茶杯放到桌子上。
⑪“你小子尽给我惹事,骨头又痒了,想挨揍啊——”他父亲说着就要打他,我连忙制止,“怎么又要打,不是和你说了吗?别总是打孩子。”
⑫“不是,这野小子自从我和他妈离婚后就没人管,没办法。我也下岗了,一个人忙着照看书摊,难得有时间在家。他要是有空就到我书摊来帮我照看,喜欢看动漫书,没事时也瞎画,我看他有这兴趣就给他报了个绘画班。呵呵——老师,您瞧,这墙上的奖状是他得的奖。”
⑬我按他指的方向看去,这才注意到墙上贴着好几张奖状。他的书桌上也散落着一些他画的漫画,有各种可爱有趣的人物,惟妙惟肖。我顺手拿起一张来看,这时他父亲迅速地收拾起来,说道:“老师见笑了,小孩子瞎画着玩,上不了台面的。”
⑭我笑道:“其实,你儿子挺有天赋的,画的不错,他画我的那张我还留着呢,别说还蛮像。”
⑮“对不起,老师!我不是有意画您,我当时只是觉得您上课很有精神,所以不知不觉就画了下来。”潘小锋有点委屈地说道。
⑯“潘小锋,既然你有这方面的天赋就应好好培养,如果有兴趣,可以向这方面发展,创作出更好的动漫画。”我还是用老师的本职口吻教育他,“以后要是有这样的活动,希望你能发挥出你的特长哦,为班集体争得荣誉!”
⑰“我会的,没问题。”他豪言壮语地答应了。
⑱我欣慰地点点头,说:“好了,天也晚了,我也该走了。”说着便走了出来,他父亲忙说道:“那我送送您吧!”
⑲“不用,我一个人走就行了。好好培养你儿子,他会有出息的。”
⑳告别了他父子俩,我走在星光和街灯掩映的路上。我抬头望着天空,繁星满天,装饰着静谧的夜,忽然发现一颗微小的星星正闪着微弱的亮光。脑海里不禁浮现出潘小锋天真可爱的神情,我沉思良久,觉得他就像天空中的那颗最小的星星,虽然小其实也一样会发光。

同类题3

阅读理解

    Green tree ants are important builders in the rainforest. They're like the worker bees of the ant world. The native forest of Thala Beach Nature Reserve is the natural home of these insects.

    They climb all over the tree that contains their nest and protect it from enemies with great fierceness. The ants are often in the fruiting trees of Tropical North Queensland. When an animal tries to help themselves to some tasty fruit, they find themselves attacked by a powerful, frightening army of green tree ants! Their bite is not very painful but many ants attacking at the same time can be extremely uncomfortable.

    The nests are large and constructed by sticking the leaves at the end of branches together to create a home looking roughly like a globe. Most of the nest construction and weaving is conducted at night. A mature colony of green tree ants can hold as many as 100,000 to 500,000 workers and may include as many as 12 trees and contain as any as 150 nests. Green tree ant colonies have one queen and a colony can live up to eight years.

    However, the ants are so busy that they fail to spot a dishonest figure. There is a spider called the Salticid spider, or the jumping spider, as they are sometimes referred to, which has excellent eyesight and is only active during daylight, weaving a protective covering of silk to spend the night in. Interestingly, the Salticid spider does not look like a green tree ant. Instead, it chemically copies green tree ants' smell. Effectively pretending to be an ant, it goes into the green tree ants' nest, enters the nursery and feasts on their babies. Green tree ants don't have good eyesight and smell everything with their antennae (two long thin parts on an ant's head). Therefore, the ants think the spider is another ant and ignore its presence within the nest.

    Next time, as you wander around Thala's native forest, keep an eye out for these busy little creatures. Look up into the trees and you'll likely spot their nests.