be good at后应该接名词，动名词，ski的意思是滑雪，是个规则变化动词，其动名词形式是skiing，直接加ING
楼上少写个I应该是"skiing"
sking后面反正要接名词，或者动名词
ski 词性1：n.滑雪板 词性2：vi.滑雪skiing n. 滑雪术；滑雪运动填skiing
是 good at doing sth.加动词ing
skiingbe good at doing sth.
