(1+3x)n(其中n∈N且n≥6)的展开式中x5与x6的系数相等,则n= [ ]
A.6
B.7
C.8
D.9
答案:B
China’s New Food Act provides for a food recall system to producers have to stop production their food isn’t up to standards.
A.that; if
B.where; if
C.which; when
D.when; where
适用于热结旁流的治则是()
A.热因热用
B.寒因寒用
C.通因通用
D.塞因塞用
E.寒者热之