. Cho tam giác ABC cân tại A, điểm D nằm giữa B và C. Chứng minh rằng độ dài AD nhỏ ơn cạnh bên của tam giác ABC.

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II.Practice : A.Use the correct verb forms : 1. Do you mind if I (take) ................. a photo? 2. Would you mind (buy).................. me some vegetables for dinner? 3. Do you mind (open).................. the window? 4. Would you mind if I (stay)..................with you for a week? 5. Do you mind (help)................... her to finish her work? 6. Would you mind if I (turn).................. off the television? 7. Would you mind (leave)................ us alone? 8. Would you mind if I (give) .................heryour book from the shelf? 9. Do you mind (take)...................... these books home? 10. Would you mind if I (sit) .................here? B.Transformation : 1. May I turn off the television? => Would you mind............................................................ ? 2..Please turn the music down. => Do you mind................................................................... ? 3.. Is it all right if I use your phone? =>Do you mind .................................................................... ? 4.. Could you fill in this form please? => Would you mind............................................................... ? 5. Do you mind if I open the windows? => Would you mind.................................................................. ? 6. Can I sit here? => Would you mind ................................................................ ? 7. Would you mind if I watched that film? => Do you mind ..................................................................... ? 8. Can I get the password? => Do you mind ...................................................................... ? 9. Can you help me with my luggage? => Would you mind ................................................................ ? 10. Do you mind my smoking? => Do you mind .................................................................... ?