1. burn the midnight oil: تا بوق سگ مطالعه كردن

 study very late at night

 - Sandy burned the midnight oil last night.

 2. do back-breaking work: كار كمرشكن انجام دادن

 do very difficult physical work

 -He is demanding a back-breaking work from me.

 3. fall down on the job:   مثل خر تو گل گير افتادن

 fail to work

 - John often falls down on the job.

 4. good off:   پشت گوش انداختن- دل به كار ندادن

 not work seriously

 - Mary often goofs off at work, and rarely works seriously.

 5. hit the books:   سخت مطالعه كردن

 study in a serious way

 - John hit the books when he was student.

 6. keeps one's nose to the grindstone:  خر كاري

 work hard all the time

 -Mark keeps his nose to the grindstone, and never stops working.

 7. work like a dog: مثل خر كار كردن

 work hard and seriously

 - He works like a dog all the time.

  8. work one's finger to the bone: تا آخرين نفس كار كردن

  work very hard

 -He works his fingers to the bone as a student.

related to idiom and fixed phrases