stifle的现在分词是哪个

　　例句：

　　The government failed to stifle the unrest.

　　政府没有制止住动乱。

　　They hope the new rules will not stifle creativity.

　　他们希望新规则不会压制创意。

　　These measures will have the effect of stifling competition.

　　这些措施会产生扼杀竞争的后果。