1.read-__read__

2.begin-__began__

3.watch-__watched__

4.see-__saw__

5.buy-__bought

6.have-__had__

7.speak-__spoke__

8.hold-__held__

9.do-__did__

10.play-__played__

Biểu thức  sin α + sin 2 α 1 + cos α + cos 2 α bằng 

A.  - cos α

B.  c o t α

C. - tan α

D.  tan α