[答案]
Icouldn'tplaybadmintonwellbefore.
[解析]
考查陈述句的肯定形式。首先根据所给词汇及标点,可确定组合的句意是:以前我羽毛球打得不好。I我,做主语,放于句首;couldn't不能,放在主语后;play badminton打羽毛球;well好;before以前,放于句尾,结合英语的表达习惯作答。连词成句为:I couldn't play badminton well before.
故答案为:I couldn't play badminton well before.
[点评]
本题考查了"陈述句否定形式,",属于"基础题",熟悉题型是解题的关键。