When he (come) ------------ yesterday, she (wash)---------------- the dishes.

. I last (meet ------------ him three years ago and since then I (not see)- ---him

1.They (eat) -----------------everything by the time I (arrive) ------ at the party.

2. When I (find)---- ----- my purse, someone (take) -----------the money out of it

3. By the time I (get)------------------ into town, the shops (close)-----------

4. When they (get) ------------------- to the station, the train (leave)-----

5. By the time you (get) --------------------her latter, she (arrive) -------- -------in Paris.

6. The police (pay)------------------ no attention to Clare's complaint because she (phone) --------------them so-----------many times before.

7. I (go)------------- to the post office to ask about my package, but they (say)------------------ that it (notarrive) yet.

8. When I (look) ------------------at the new dress for half an hour, I (ask) ---------------how much (cost)--------

9. I (give)-------------- Mr. Brown your letter when I (see)----------------- him tomorrow.

10. This time yesterday, I (lie) ------------------ on the beach.

11. When the phone (ring)--------------, I (have)---------------------- a bath.

12. Wait until I (catch) ------------------you.

13. Every Friday David (play) ----------------- -------------football.

14. He sometimes (come) ---- -------- to see his parents.

15. I last (meet ------------ him three years ago and since then I (not see)- ---him

16. When he (come) ------------ yesterday, she (wash)---------------- the dishes.

17. We (study)----- ----- the lessons while she (do)------------------- her exercises.

18. They (live) ---- in New York for ten years before they (move).-------- to London.

19. Right now I (attend)--------------- class. Yesterday at this time I (attend)----------------- class.

20. I (visit)---- -------------- my uncle many times when I (be)------------- a child.

21. You (be)----- ------ here before?- Yes, I (spend) -----my holiday here last year.

22. I (spend) -----------a lot of time traveling since 1 (get)-------- ----- the new job.

23. We (finish) ---------------our dinner half an hour ago.

24. The farmers (work) --------------- in the field now.

25. Mrs. Green always (go) ------ to work by bus.

we ( study ) ____ the lesson while she ( do ) ___ her exercises

when he ( come ) ___ yesterday , she ( wash) ___ the dishes

i last ( meet ) ___ him three years ago and since then i ( not see) ____ him 

1.john ( be )__ good to me since I ( be ) ____ a liite girl . H hope i ( not forget ) ____ his kindness

2. i ( come ) ___ from Italy but I ( study ) ___ Enland at the moment 

3. He (come) _____ back then minutes ago and ( turn ) ____ TV very loudly . My grandmother( sleep ) ____ then so ( tell ) ___ him to turn it off

4. what you ( do ) ______ at the moment ? I (write) ____ a report

45. While i ( walk ) _____ to school yesterday , morning , I (see) _____ Jane , we ( say)____ hello and ( walk ) ___ the rest way to school together.  

1. When i ( come ) ___ to her house this morning , she ( work ) ___ in the garden . she often ( do )__ gardening when she ( have ) ___ time 

2. In the evening , i often ( play ) _____ chess with my next door neighboor . I ( play ) ___ chess with him since I ( come ) ___ to live here ten years ago

3. Tom ( have ) _____ av accident four days ago . He ( be ) ___ in the hospital now . He ( be) ___ in the hospital since he ( have ) ___ the accdident 

4. yesterday evening , Lorry ( come ) ____ into the room , (open ) ___ the window ( turn )____ on the light , and ( begin ) ___ to read . 

we ( look ) ___ at the picture when the light went out 

yesterday , i (meet)___ the woman wo ( help) ___ us before

while she (talk ) ____ on the phone , the children ( start)____ fighting and ( break)____ a window 

1.my younger brother i ( start) _____ to learn English when he ( be ) ____only seven years old 

2) I (meet ) tom while ( go ) _____ to post office yesterday . i ( ask ) ____ him ( go ) ___ with me . Both he and i ( want ) _____ (sent)  _______ some letter

3) George ( come ) _____ from Sydney . he ( be )______ 20 year old and he ( be ) _____ student . what he (do)___ everday 

How many times you (see)_________________ him since he (come) ___ to vist new year?

7  Cấu hình eletron lớp ngoài cùng của ion âm  là  3s² 3p⁶ thì cấu hình electron của nguyên tư tạo ra ion đó có thể là 
(I)   1s² 2s² 2p⁶ 3s²                           (IV)   1s² 2s² 2p⁶ 3s² 3p⁴       
(II)  1s² 2s² 2p⁶ 3s² 3p⁵                        (V)  1s² 2s² 2p⁵
(III)   1s² 2s² 2p⁶ 3s¹                          (VI) 1s² 2s² 2p⁴