YOU SAID:

my dog is very efficient at fetching the ball but some times he doesn't that good

INTO JAPANESE

私の犬はボールをフェッチで非常に効率的ですが、いくつかの時間彼は良いことをしていません

BACK INTO ENGLISH

My dog ​​is very efficient at fetching a ball but for some time he has not done a good thing

INTO JAPANESE

私の犬はボールを取り出すのが非常に効率的ですが、しばらくの間は良いことをしていません

BACK INTO ENGLISH

My dog ​​is very efficient at removing the ball, but I have not done a good thing for a while

INTO JAPANESE

私の犬はボールを取り除くのが非常に効率的ですが、私はしばらくの間良いことをしていません

BACK INTO ENGLISH

My dog ​​is very efficient at removing the ball, but I have not done a good thing for a while