Contact us
Choose a category below so we can get back to you as quickly as possible.
原式=a−b+ca+b−c-a−2b+3ca+b−c-b−2ca+b−c=a−b+c−a+2b−3c−b+2ca+b−c=0.故選A.
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.