阅读理解
Name: Kelsey
Age: 22
I can sing and dance. I can play the violin and the piano, but I can't play the guitar.
Name: Paul
Age: 13
I can sing, but I can't dance. I can play the trumpet and the guitar but I can't play the violin.
设抛物线y2=4x的焦点为F，准线为l．已知点C在l上，以C为圆心的圆与y轴的正半轴相切于点A．若∠FAC=120°，则圆的方
程为____．
如图是北美草原犬鼠洞穴的橫截面示意图．它有两个出口，洞口A表面隆起，洞口B表面平坦．则下列分析正确的是（ ）
