K12教育赛事综合服务平台
聚乐之家官方网站
下载聚乐之家官方App
专注青少年竞赛题库网站
str1 = "cat dog cat dog cat dog" str2 = str1.replace("cat", "mouse", 2) print(str2)
cat dog mouse dog cat dog
2 dog mouse dog cat dog
mouse mouse dog mouse mouse dog cat dog
mouse dog mouse dog cat dog