I will sing "Happy birthday" _____ him in English. [ ]
A. on
B. of
C. for
答案：C
抛物线y=ax2+bx+c（a≠0）上两点，当x取-1与3时，y值相同，抛物线的对称轴是______．
下列哪些是异位妊娠（）①腹腔妊娠②子宫角妊娠③残角子宫妊娠④子宫颈妊娠⑤输卵管妊娠⑥卵巢妊娠
A.②③
B.①②③
C.①②③④
D.①②③④⑤⑥
E.⑤
