3.DS A container consists only copper ,tin and c什么 ,if the container weighs 60 pounds ,then the weight of the copper is (1) copper is 1/10 of the container (2) tin is 2/5 and the c什么is 5/10 of the container 这题不难,但题目很绕,选项的表达不是我写的这样。但意思一样,我题目读了半天 他的表达是 the weigh by copper 什么的 4.ps (X+1)(X+4)/x(X^2+6X+8) 化简 5 ds xy^2/z^3 <1 (1) y-x>1 (2)x<z<y 选e