1.B

2.D

3.B

4.A

5.B

1.B
2.D
3.B
4.A
5.B
X.
1.Students have Vietnamese lessons on Saturdays
2.American students don't have English lessons on Saturdays
3.They only have classes in the morning on weekdays 
4.Vietnamese students have three months off for vacation 
5.The students have their exams in May
6.They always do their homework in the evening
7.She is watching television at the moment
8.They aren't going to enjoy the concert
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