какое количество сульфида алюминия получится при взаимодействии 4 моль алюминия с серой?

Из двух деревень навстречу друг другу одновременно вышли два лыжника.Через 2 минуты растояние между ними стало 500метров.На коком растоянии находятся деревни,если скорость одного лыжника 200м/мин,а другого-300ь/мин

Раскройте скобки, употребляя глаголы в Past Simple или Past Perfect.

1. Не(to study) French before he (to enter) the university. 
2. Lanny (to say) that he (to get) his education in Cape Town. 
3. The boy (to want) to act the main part in the play because he (to organize) the theatre. 
4. Lanny (not to know) who (to attack) him in the darkness. 
5. The girl (to be) glad that she (to find) a seat near the window. 
6. Suddenly he (to remember) that he (not to ring) her up in the morning. 
7. By the time the train (to reach) the city, he (to make) friends with many passengers. 
8. When his uncle (to leave), he (to hurry) to the station to book a ticket. 
9. She (to think) that Gert and Lanny (to quarrel). 
10. By the time we (to come) to see him, he (to return) home. 
11. During the holidays my friend (to visit) the village where he (to live) in his childhood. 
12. When they (to enter) the hall, the performance already (to begin). 
13. When I came home, my mother (to tell) me that she (to receive) a letter from grandfather. 
14. Where you (to work) before you (to enter) the institute? 
15. By two o'clock the teacher (to examine) all the students. 
16. On my way to school I (to remember) that I (to leave) my report at home. 
17. All my friends (to be) glad to hear that I (to pass) all the examinations successfully. 
18. Poor Oliver (to lie) unconscious on the spot where Sikes (to leave) him. 
19. He (to open) his eyes, (to look) around and (to try) to remember what (to happen) to him. 
20. All the passengers (to see) at once that the old man (to travel) a great deal in his life.

составьте схемы, отображающее строение атомов: а) азота; б) неона; в) натрия.