Mẹ và Khoa cùng làm chung nhau một công việc thì sau 48 phút sẽ xong. Cũng công việc đó, mẹ làm một mình trong 63 phút, sau đó Khoa làm trong 28 phút thì hoàn thành. Thời gian mẹ làm một mình để xong toàn bộ công việc là bao nhiêu ?

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IV. Put the words in order to make a question. Then write a short answer. 1. homework/ you/ have/ your/ finished? (yes) _________________________________ _______________________ 2. your/ to/ been/ ever/ father/ has/ London? (no) _________________________________ _______________________ 3. done/ this/ you/ exercise/ have/ before? (no) _________________________________ _______________________ 4. had/ Jenny/ yet/ has/ lunch/ her? (yes) _________________________________ _______________________ 5. the/ ever/ story/ heard/ before/ have/ they? (no) _________________________________ _______________________ 6. rained/ has/ today/ it/ a lot? (yes) _________________________________ _______________________ 7. at/ you/ have/ seen/ a/ the/ play/ theatre? (no) _________________________________ _______________________ 8. been/ they/ friends/ have/ ten/ for/ years? (yes) _________________________________ _______________________ V. Complete the sentences with the correct tense of the verbs in brackets. Use the past simple or the present perfect tenses. 1. I’m really hungry. I ______________ (not have) lunch yet. 2. We ______________ (not have) a maths class last week. 3. Keith’s not home now. He ______________ (go) to the beach this weekend. 4. My family ______________ (move) to Canada in 2010. 5. _________ you ever __________ (visit) San Adarino? 6. He ______________ (live) in London for two years when he was a student. 7. __________ Jenny __________ (go) to the dentist yesterday? 8. They ______________ (work) in this company since 2001. 9. _________ you __________ (see) Joana recently? 10. Jim ______________ (break)his leg in a skiing accident two years ago.