Viết dạng đúng của từ

1 He (see) .......Dorothy sine last Saturday 
2 It we need some help,we (ask).......
3 they (start)...... Writing to each other eight years ago
4 . Robots can (do) ....... The housework for human now.
5 He (study)....... English sine last year
6 The 2012 Olympic Games(be)...... Held in Landon
7 If we win the money, we(buy)....... A new house 
8 I ( not be) ..... Very happy yesterday