《江西第一次全省农民代表大会宣言》中提到,“几千年来被压迫被剥削被轻视的我们,此次因组织了农民协会,才能在江西政治中心地点——南昌,开我们……第一次代表大会”,“江西农民久受军阀压迫,一旦闻革命军到来,即出死力帮助”。此次大会召开于
A.辛亥革命时期 B.国民革命时期
C.抗日战争时期 D.新中国成立前夕
以A、B、C为原料制取药物AspirinSustained-ReleaseTablets(缓释阿司匹林)的合成路线如图:
已知:ⅰ.A、B为烃,其中A的产量可作为石油化工水平的标志;
ⅱ.。
回答下列问题:
(1)Z所含官能团名称为___。
(2)B和Y的结构简式为__、__。
(3)完成方程式:
①X→CH2OHCH2OH__。
②C→__。
(4)满足以下条件的的同分异构体共有__种(不含立体异构),其中核磁共振氢谱峰面积比为6:1:1的同分异构体的结构简式为__。
a.能发生水解反应 b.能与钠反应放出氢气 c.能发生银镜反应
(5)以乳酸()和甲醇为原料,其他无机试剂任选,设计合成
的路线:__。
Most cell phone companies design models especially for kids. But parents are usually the ones buying the phones. According to a July 2012 study, 56% of parents of children aged 8 to 12 have given their children a cell phone. According to a recent YouthBeat survey, 12 is the magic number. It is the most common age for kids to get their first cell phone. But 13% of children aged 6 to 10 already have one. The number goes up with age.
Procell phone people, including many parents, notice that cell phones help kids keep in touch with their friends and families. They believe that cell phones are an important tool in a dangerous situation. Kids can stay connected with their parents at all times, whether it's to ask for a ride home from soccer practice or to receive a text message moments before a big game. Plus, some cell phones designed for kids can be controlled with settings that allow the phone to only be used in parentapproved ways. What's the harm in that?
But other people are worried about the health and safety effects of kids' cell phones. They believe that kids with cell phones will spend less time playing outside or hanging out with friends, and that sending text messages or making phone calls while doing homework is bad for concentration. They say that kids are spending too much time texting instead of talking to each other. “Our brains developed to communicate face to face,” says Gary Small, a professor of psychiatry at the UCLA School of Medicine in California. “A lot of this is lost with texting.”
And some experts are also concerned about possible health risks. They worry that radiation—or energy waves—produced by cell phones could be harmful to young people. To be safe, parents should not let them talk long on the phone.
篇章导读:本文是一篇议论文。现在大多数孩子都拥有手机,但手机作为现代科技的产物,也犹如一柄“双刃剑”。因此,针对孩子们持有手机的现象,家长和专家们都有着不同的观点。一些人持支持的态度,也有很多人担心手机会给孩子们带来负面影响,建议采取相应措施帮助孩子们趋利避害。
9.The recent YouthBeat survey suggests that ________.
A.the number twelve can bring us good luck
B.most kids are eager to have their own cell phones
C.many kids have their first cell phone at the age of 12
D.more than half of the parents can afford to buy cell phones
10.Procell phone people probably refer to those who think that kids ________.
A.mustn't own cell phones
B.should have cell phones
C.had better make more friends
D.may lose touch with others
11.According to Gary Small, cell phones ________.
A.waste us a lot of money
B.are of great benefit to many kids
C.bring much pleasure to most of the kids
D.reduce kids' facetoface communication
12.The author's attitude toward the fact that kids have cell phones is ________.
A.supportive B.objective
C.negative D.optimistic
有科学研究提出 : 锂电池负极材料 (Li) 由于生成 LH 而不利于电池容量的保持。一定温度下,利用足量重水 (D 2 O )与含 LiH 的 Li 负极材料反应,通过测定 n(D 2 )/n(HD) 可以获知 n(Li)/n(LiH) 。
已知: ①LiH+H 2 O=LiOH+H 2 ↑
②2Li(s)+H 2 ⇌2LiH △H < 0
下列说法不正确的是
A . 可用质谱区分 D 2 和 HD
B . Li 与 D 2 O 的反应: 2Li+2D 2 O=2LiOD+D 2 ↑
C . 若 n(Li)/n(LiH) 越大,则 n(D 2 )/n(HD) 越小
D . 80℃ 反应所得 n(D 2 )/n(HD) 比 25℃ 反应所得 n(D 2 )/n(HD) 大
试验田编号 | |||||||||||
(棵/) | |||||||||||
(斤/棵) |
技术人员选择模型作为
与
的回归方程类型,令
,
相关统计量的值如下表:
由表中数据得到回归方程后进行残差分析,残差图如图所示:
(1)根据残差图发现一个可疑数据,请写出可疑数据的编号(给出判断即可,不必说明理由);
(2)剔除可疑数据后,由最小二乘法得到关于的线性回归方程中的
,求
关于
的回归方程;
(3)利用(2)得出的结果,计算当单位面积播种数为何值时,单位面积的总产量
的预报值最大?(计算结果精确到
)
附:对于一组数据,
,
,
其回归直线
的斜率和截距的最小二乘法估计分别为
,
,