材料一:巴斯德将狂犬的唾液注射到兔的体内,兔患狂犬病而死,他将死兔的脑和脊髓通过处理,弱化成疫苗,注射到正常狗的体内,狗获得了对该病的免疫力。后来,有一男孩被狂犬咬伤,不治必死,在狂犬病发病潜伏期内,巴斯德多次对其接种弱化病毒,男孩果然平安无事。
材料二:狂犬病是由狂犬病病毒引起的,它和传染性非典型肺炎、艾滋病、禽流感等同属于一类传染病,发病后几乎全部死亡。
材料三:今年元月27日,湖南浏阳某乡3岁幼女被恶狗咬伤,当日在诊所注射狂犬病疫苗,但仍于2月23日不幸死亡。专家分析,对创伤深广、严重者,除按要求注射狂犬疫苗外,还应在24小时内注射高效抗病毒血清一剂,才能有效防治。
Is there an important exam right around the corner? You might be starting to fear, thinking that there's no way for you to get a good grade because of the little time left to study. This is something all students may worry about. But you should accept the fact that you have to take the exam no matter how much you want to avoid it.
Thankfully, there are several ways to help you get at least a passing grade. You may have a try.
Get yourself together
This might sounds like silly advice, but it's actually the most important. When you fear, you may lose control over your thoughts and actions. Even if you try to study, perhaps you won't get anything in your head.
Enjoy enough sleep
It's unbelievable many students have little sleep each night. That's not something to be proud of, especially if you're sleeping so little and still failing to do
all the things. Sleep isn't for the weak, but for the wise. Your brain needs enough rest. After a good night's sleep, you'll perform much better in the morning.
Don't fear
Once the test paper is in front of you, don't be afraid. Take a deep breath and start the exam with confidence. Just like when you were reviewing, put away the problems you' re having difficulty in and come back to them later. If you have time left, go over everything to make sure you haven't made any careless mistakes.
求:若要制得2g氢气,需要甲酸的质量为多少g?
试回答:
(做出猜想)
甲同学认为:二氧化碳浓度大使蜡烛熄灭。
乙同学认为:集气瓶中氧气耗尽,蜡烛熄灭。
(查阅资料)生石灰(氧化钙)与水反应会产生大量热。
写出白磷燃烧的化学方程式:。
结论:乙同学猜想不正确,蜡烛燃烧熄灭后,集气瓶中还有氧气。
①生石灰与水反应的化学方程式,作用是。
②白磷燃烧熄灭后,用氧气传感器测得氧气瓶中仍有3.4%的氧气,所以蜡烛、白磷熄灭的原因是。
③氧气浓度对可燃物燃烧有较大影响,请你以铁丝为例,利用电加热引燃,设计实验,写出你的实验方案:。
①影响集气瓶中压强变化的因素有温度和。
②压强曲线BC段曲线变化的原因分析:。
③DE段压强突然增大的实验操作是(指出操作时机、操作方法及压强增大原因)。
材料一:英国革命的最大成果,也是它在现代民主政治创制试验方面的最大成就,就是创造了一种全新的政体……它开启了近代民主代议制的先河。
——威尔·杜兰《世界文明史》
材料二:宪政主义、联邦主义和有限政府在欧洲倒不是新颖的思想,它们溯自中世纪…美国革命使这些思想变成进步的思想。美国的影响为欧洲的发展势力增添了力量,使启蒙运动后期的思想变得更加民主。合众国取代英国,成为先进思想家的模范国家。
——【美】帕尔默《现代世界史》
材料三:我认为,政治制度必然得自根自生。纵使有些可以从国外移来,也必然先与其本国传统,一番融合娟通,才能真正发生相当的作用。否则,无生命的政治,无配合的制度,决然无法成长……。
——钱穆《中国历代政治得失》序言
试求出a的值