Giải
37. The little girl was made go to bed in time by the mother

38. If she Is not ill, she can go to school today

39. My sister has learned English since she was 6 years old

40. The car was too expensive for my father to buy

37. The mother made the little girl go to bed in time.

     The little girl__was made to go to bed in time by her mother

38. She can’t go to school today because she is ill.

     If she_were not ill, she could go to school today

39.My sister began to learn English when she was six years old.

     My sister has learnt/has been learning English since she was six years old_______.

40. The car was so expensive that my dad didn't buy it.