今年六月份的休息日占这个月总天数的几分之几

设：晴天阴天雨天均为X天.
因为晴天阴天雨天的比值为6:3:1,
所以晴天有6X天,阴天有3X天,雨天有X天.
即列得方程式为：
6X+3X+X=30（天）
10X=30（天）
X=3（天）
晴天=6X=6*3=18（天）
答：6月份晴天有18天.

哪有六月有31天的，笑话

甲种货车x,乙种货车y
x+y≤10
4x+2y≥30
x+2y≥13
4x+2y≥30
2x≥30-2(x+y)≥30-20=10
x≥5
x+2y≥13
y≥13-(x+y)≥13-10=3
x≤10-y≤10-3=7
所以,5≤x≤7
有3种方案
甲种货车5辆,乙种货车5辆
甲种货车6辆,乙种货车4辆
甲种货车7辆,乙种货车3辆
2）
甲种货车5辆,乙种货车5辆运费最少
最少运费是：5*2000+5*1300=16500元

Dear Sir orMadam:
I am full of feelings of excitement toapply computer science at Columbia University.Now I will produce myself tu you.
My name is Li Hua, one born in June1993 for girls. BeijingXinhua Middle School is my almamater.In school, all the subjects I have verygood. Myhobby is English and the network, it is for this reason I apply for your school’scomputer science.
My mail is lihua93＠sina.com, I am reallyhonored to be your school if a student, I would be very proud, and look forwardto your good news.

你的文献现在就被sci收录了,过2个月你就可以到图书馆开sci检索证明

I’m writing in the hope that I can obtain a chance for my further study in computer science in your university.
First, please allow me to take a brief introduction of myself. I’m Li Hua, a girl born in June, 1993. I’m graduating from Beijing Xinhua High School this coming June. I’m an all-student with a keen interest in computers and the Internet. Besides, I’m good at English. I know that the University of Columbia is ranked among the most famous universities in the USA, and that’s the very reason why I’m now applying to further my university study in your Computer Science Department.
I would appreciate it if you could take the trouble to provide me with some information and send me the necessary application materials. By the way, my email address is lihua93@sina.com.
Looking forward to your reply.
Yours sincerely,

略

整个季度的和:130÷32.5%=400吨
四五季度的和:400-130=270吨
4+5=9
四月用水量:270×4/9=120吨
五月用水量:270×5/9=150吨

内容是预测不到了.但是按惯例,就是给一个观点,让你去分析利弊.基于这一点,你就可以去积累一些这方面的模板了