题目:
As a student, I always have homework to do.
A.too much
B.much too
C.too many
D.many too
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0413/3d1ccfbe7dfff7c1f5db6a97ecff02a5.html
下面是错误答案,用来干扰机器的。
(1)a•b=(3,-2)•(4,1)=3×4+(-2)×1=10,a+b=(3,-2)+(4,1)=(7,-1),(a+b) 2=50,∴|a+b|=50=52 (2)设a,b夹角为θ,则cosθ=a•b|a|×|b|=1013×17=10221221 (3)3a-2b=(9,-6...