请问美国一通的期限？

请问美国专利局答复一通的期限是多久？在什么情况下可以延期，最长可以延期多久？收费情况如何？指官费。

多谢！

哪位知道回复一下哦
先谢过了

发文之日起三个月内，随便编一个理由就可以延期。费用第二栏是小企业收费标准。
Patent Extension of Time Fees  
1251/2251 1.17(a)(1) Extension for response within first month  120.00 60.00
1252/2252 1.17(a)(2) Extension for response within second month  460.00 230.00
1253/2253 1.17(a)(3) Extension for response within third month  1,050.00 525.00
1254/2254 1.17(a)(4) Extension for response within fourth month  1,640.00 820.00
1255/2255 1.17(a)(5) Extension for response within fifth month  2,230.00 1,115.00

谢谢message!

真的非常感谢！

message wrote:
发文之日起三个月内，随便编一个理由就可以延期。费用第二栏是小企业收费标准。
Patent Extension of Time Fees  
1251/2251 1.17(a)(1) Extension for response within first month  120.00 60.00
1252/2252 1.17(a)(2) Extension for response within second month  460.00 230.00
1253/2253 1.17(a)(3) Extension for response within third month  1,050.00 525.00
1254/2254 1.17(a)(4) Extension for response within fourth month  1,640.00 820.00
1255/2255 1.17(a)(5) Extension for response within fifth month  2,230.00 1,115.00

法定期限是六个月，但前三个月是不需要给钱的，后三个月时需要用钱买的，延至后三个月需要说明理由吗？我记得是不用的。