单项式2x2y的的系数是( ),次数是( )。
2;3
It’s ________ most beautiful furniture , by which I was struck at the first sight and I determined to take ________ possession of it some day .
A.the ; ×
B.a ; /
C.a ; the
D./ ; /
用对观测列进行统计分析的方法,来评定标准不确定度,称为A类不确定度评定。