I. Do as directed 1. Johnny said to his mother, ''I don't know how to do this exercise'' Johnny told his mother..... 2. ''Don't come back before one o'clock'', advised my brother My brother advised me..... 3. I ofen went fishing when i was young I used... 4. My friend said, '' Are you going to leave tomorrow?'' My friend asked me.... 5. I said Bill, '' What time did you go to bed last night?'' I asked Bill....... 6. It's a pity. I can't help her with her business I wish...... 7. ''We are waiting for the school bus'', said the children The children said that .... 8. ''Listen to me and don't make a noise'', said the teacher to his students The teacher asked his students.... 9. Because my sister studied hard, she completed her exam successfully (Rewrite using ''so'') My sister..... 10. ''Let's go for a walk'', said tam Tam suggested....

Phương pháp giải bài toán Hóa học:

1. Viết phương trình phản ứng giữa hỗn hợp MgO, Fe2O3, CuO và dung dịch H2SO4.
2. Xác định số mol dung dịch H2SO4 cần dùng để tác dụng hoàn toàn với hỗn hợp oxit.
3. Tính khối lượng muối thu được từ số mol axit sunfat đã dùng.

Câu trả lời cho câu hỏi trên: B. 80 gam.