A:①④
B:②③
C:①③
D:②④
bì pīn dù àn dǒng gāng
冈____ 懂____ 渡____ 蔽____ 案____ 拼____
My brother can’t ____ (骑马).
A. doctor B. nurse C. teacher D. farmer E. singer F. writer
⑴ ____ ⑵ ____
⑶ ____ ⑷ ____
⑸ ____ ⑹ ____
语句甲:动点P到两定点A,B的距离之和|PA|+|PB|=2a(a>0 ,且a为常数);语句乙:P点的轨迹是椭圆,则语句甲是语句乙的( )