be in good 在...表現(xiàn)良好,在...有效果 但be good in 極少作文固定短語
It has been proved to be good in practice result.實踐效果良好.
To have fine political and professional quality and to be good in conduct.
有良好的政治、業(yè)務素質和良好的品行;
be good at 擅長于 ...at后面跟名詞或動名詞（即動詞+ing）
Alex is very good at languages.擅長語言
She's good at making things.