题目

若是关于的方程的一个根，则的值是（ ）A. -3 B. -1 C. 1 D. 3 答案：【答案】A【解析】根据一元二次方程的解的定义得到n2+mn+3n=0，然后两边除以n即可得到m+n的值．把x=n代入x2+mx+3n=0得n2+mn+3n=0，∵n≠0，∴n+m+3=0，即m+n=-3．故选A．______ left before the deadline, it doesn’t seem likely that John will finish the job.A．Though such a short timeB．Because such a short timeC．With such a short timeD．As such a short time