端午节的由来小知识

已知数组a=（-1,3,x）,b=（y,2,3）,c=（0,z,5）,若2a+b=c,求x,y,z的值. 如果x,y,z∈R,且x+y+z=a(a>0),x^2+y^2+z^2=a^2/2,求证0≤x≤2a/3,0≤y≤2a/3,0≤z≤2a/3. 猫头鹰的天敌是什么?我觉得他没有天敌他是猛禽,要有也是人 田鼠天敌是什么? 猫头鹰天敌是什么? only 11 people ______the shipwreck.survived after 获救 survived through安然度过 为什么都不能用 只能用survived 猫头鹰的天敌回答—人——的可以去死了 在央视不知道几台 看过 有只猫头鹰被天敌攻击的录像 也是猛禽 叫什么忘了 知道的朋友说下别说没有天敌之类的话 了 猫头鹰的天敌是什么啊? ★★2个初二英语适当形式填空★★急There was a terrible acdident on the road last night,and ___(luck) two men were killed.The old building in our town has stood there for ____ (century). 我想要一些蜂蜜和苹果用英语怎么说 急,为啥叫东周西周,东汉西汉,而不叫南周北周呢?而北宋南宋就是南北! 为什么先由“西周”再是“东周”,先是“西汉”再是“东汉”? effort作啥解释是可数啥解释是不可数? 填有含字母的式子钢笔的单价是圆珠笔的3.6倍,圆珠笔每支x元.钢笔每支是 元；钢笔比圆珠笔每支贵 元. effort可数吗? effort是什么意思? Peter always feels tired.What's wrong with_____?A he B himself C his D him Mr Li is always s_____ with himself in evening 填空 英语首字母填空题!Bill Gates was born in USA in 1955.When he was at school,he n______ took a book home to study or attended maths classes.He then went to Harvard,but left w______ getting a degree.By the age of forty-one,he was one of the world I like dreaming,and I always think about what my future will be like in 5 years. 用含有字母的式子可以简明地表示计算什么和运算什么,还可以表示什么关系 It's always been about me myself and I If all relationships were nothing but a waste of time I neve it is nothing very secret, but it is always ______ to keep quiet about theseA, or rather B. as well as C. either D. as well这题选什麼?为什麼?啊哦，答案是D，就是不知道为什麼…… 猫头鹰为什么在晚上才开始捕食呢? 猫头鹰怎么会在晚上捕食 猫头鹰靠什么捕食超声波?次声波?视觉?听觉? “得地本虚心”是什么意思 猫头鹰捕食行为是学习行为吗 王安石的翻译 谦虚不好吗 He is confident,he always feels____about himself.A.better B.well C.good D.best he cares only about himself中的only可以放在he后面么,副词的位置能怎么放