【简答题】All of the following are traffic signs except ________. [ ]
【简答题】我国北方曾持续干旱,为此农业家建议尽快发展高能抗旱保水剂。保水剂是一种强吸水树脂,能在短时间内吸收自身重量几百倍至上千倍的水分。聚丙烯酸钠就是一种高吸水性树脂。下面是丙烯合成聚丙烯酸钠的化工流程: 请回答下列问题: (1)上述反应中属于加成反应的有______,反应⑧的反应类型为___________; (2)写出A的结构简式:______________,D中的官能团有_________; (3...
【单选题】John is doing very well in school and it is quite ______ that his mother should be proud of him.
【简答题】已知函数f(x)=ax 3 +bx 2 +cx+d(a,b,c,d∈R),且函数f(x)的图象关于原点 对称,其图象在x=3处的切线方程为8x-y-18=0 (1)求f(x)的解析式; (2)是否存在区间[m,n],使得函数g(x)的定义域和值域均为[m,n],且其解析式为f(x)的解析式?若存在,求出这样一个区间[m,n];若不存在,则说明理由.
【单选题】The volunteers for the Shanghai World Expo are busy from dawn ______ dust but they feel very proud of it.
【简答题】已知函数f(x)=ax 3 +bx 2 +cx+d(a,b,c,d∈R),且函数f(x)的图象关于原点对称,其图象在x=3处的切线方程为8x-y-18=0。 (1)求f(x)的解析式; (2)是否存在区间[m,n],使得函数f(x)的定义域和值域均为[m,n],且其解析式为f(x)的解析式?若存在,求出这样一个区间[m,n];若不存在,则说明理由。
【简答题】The following are all traffic signs except ____. [ ]
【单选题】()signal the direction of a writer’s thoughts and they are like the road signs that guide travelers.
【单选题】已知点P(m,n)和点A(1,2)在直线L:3x+2y-8=0的异侧,则()
【单选题】已知点P(m,n)和点A(1,2)在直线3x+2y-8=0的异侧,则 ( )