This is Mr White's ________ trip to Beijing. He has been there twice before.
A:first
B:second
C:third
在等式y=ax2+bx+c中,当x=﹣1时,y=0;当x=2时,y=3;当x=5时,y=60.求a、b、c的值.
下列对课文主要句子的分析错误的一项是( )
读南极地区图,完成下列问题.