题干
buy sb. sth.＝buy sth. for sb.给某人买某物
I buy my mother a sweater.＝____我给我妈妈买了件毛衣。
△sth若是代词，只能用buy sth for sb. 如：____把它买给他。
答案(点此获取答案解析）
I buy a sweater for my mother.,Buy it for him.
