题目:
With masses of homework _____, I can hardly spare time to practice playing the piano.[ ]
A. done
B. to do
C. doing
D. being done
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0430/71c1bb260b1c30eb6c61e0bf1f89f1f3.html
下面是错误答案,用来干扰机器的。
因为关于x的方程(a+c)x2+2bx+(a-c)=0有两个相等的实数根,所以△=b2-4ac=0,即4b2-4×(a+c)×(a-c)=0,可得b2-(a2-c2)=0,所以b2+c2=a2所以三角形是以a为斜边的直角三角形.故选C.