4Al + 3O2 -> 2Al2O3 ( nhiệt độ cao )
Al2O3 + 6HCl -> 2AlCl3 + 3H2O
AlCl3 + 3NaOH -> Al(OH)3 + 3NaCl ( Al(OH)3 kết tủa )
2Al(OH)3 -> Al2O3 + 3H2O ( nhiệt độ cao)
2Al2O3 -> 4Al + 3O2 ( nhiệt độ cao)

31.hardly -> hard
32. had I -> I had
33. turning -> to turn
34. said to -> told
35. sending -> to send
36. brought -> grown
37. kind -> kindly
38. to -> off
39. than -> to

Theo mình là cường độ dòng điện vì I các lớn thì đèn sáng càng mạnh :)

1. Is it a beautiful house ?
2. He often goes to work by car
3. Why don't we go to Dam Sen park ?

1. Do you like playing football ?
2. Are you fond of playing basketball ?
3. Are you keen on playing tennis ?
4. Are you interested in swimming ?
5. Do you love playing volleyball ?
6. Do you enjoy play baseball ?
....

( be keen on = be interested in = be fond of : thích )
Ý bạn là vậy hả ?

1. He asked me if I could sing that song
2. I asked him if they were cutting grass in that garden
3. He asked me if I liked fish
4. I asked him if she worked there
5. They asked me if they played guitar well
*
1. He has not been seen for a long time
2. All the lights have been turned off by Tan

1. Has devoloped ( trước since HTHT, sau since QKĐ)
2. travelled ( last summer + QKĐ)
3. Have you finished ? ( Yet -> HTHT)
Oki!!

Nêu những biện pháp khắc phục những khó khăn về điều kiện tự nhiên của vùng trung du và miền núi bắc bộ .
P/s : Help me, sắp phải nộp bài rùi !!