1,3-丁二烯存在cis和trans两种形态,其中cis形态更易与烯烃发生【4+2】环加成反应。()
此题为判断题(对,错)。
此题为判断题(对,错)。
颅面血管瘤和结节性硬化两种疾病都存在:()
A、脑水肿
B、脑实质钙化
C、中线移位
D、脑室扩张
E、颅板增厚
粮食中水分有两种不同的存在状态,一是(),二是结合水。
A.自由水
B.离子水
C.结晶水
D.混合水
按可燃物的类型和燃烧特性不同,下列物质发生火灾属于A类火灾的是_____。
A.甲醇
B.丁二烯
C.纸盒
D.铁屑
证券问的联动关系由相关系数ρ来衡量,ρ的取值总是介于-1和1之间,ρ的值为正,表明()
A.两种证券间存在完全的同向的联动关系
B.两种证券的收益有反向变动倾向
C.两种证券的收益有同向变动倾向
D.两种证券间存在完全反向的联动关系
下列烯烃中哪个不是最基本的有机合成原料“三烯”中的一个。()
A.乙烯;
B.丁烯;
C.丙烯;
D.1,3-丁二烯。
At the end of February, Bry told Ami that he would not complete the plastering in time unless she agreed to increase his payment by a further £1,000. Ami agreed to pay the increased sum in order to ensure that the job was done on time. She then thought it was only fair that she should increase the amount of money promised to Cis by the same amount.
However, on completion of the work on time Ami refused to make either of the additional payments to Bry or Cis, beyond the original contractual price.
Required:
Advise Bry and Cis whether they have any rights in law to enforce Ami’s promise to pay them an extra £1,000.
若某烃分子中的一个氢原子被溴原子取代,取代后所得化合物只有两种同分异构体存在,则该烃是()
A. 甲烷
B. 2,2-二甲基丙烷
C. 正丁烷
D. 2-甲基丁烷