Phương trình $\frac{\sin 2x}{\tan x-1}=0$ có nghiệm là
A. $x=k\frac{\pi }{2},k\in Z.$
B. $x=k\pi ,k\in Z.$
C. $x=\frac{\pi }{3}+k2\pi ,k\in Z.$
D. Vô nghiệm.

Nghiệm của pt $\tan x+\cot x=2$ là 
A. $x=-\frac{\pi }{4}+k\pi $ 
B. $x=\frac{\pi }{4}+k\pi $ 
C. $x=\frac{5\pi }{4}+k2\pi $ 
D. $x=-\frac{3\pi }{4}+k2\pi $

Choose the best answer for the following sentence:
_________ she agreed, you would have done it.  
A. If                
B. Had                     
C. Should                 
D. Would

Choose the best answer for the following sentence:
I write letters ___________ my left hand. 
A. in                
B. by                  
C. with                     
D. at

Choose the best answer for the following sentence:
She ___________ a pair of shoes from among the dozen the salesgirl'd shown he 
A. picked                 
B. selected                   
C. opted                  
D. sorted

Choose the best answer for the following sentence:
Some of the proposals ___________ . 
A. were strongly objected                    
B. strongly objected to
C. were strongly objected to                 
D. strongly objected

Choose the best answer for the following sentence:
My brother _______ his job last month and since then he _____ out of work.
A. lost - has been
B. has lost - was
C. was losing - has been
D. was loosing - was

Choose the best answer for the following sentence:
We would like to thank the local enterprises we work _______________ to organize the event.
A. on cooperation with
B. on cooperation of
C. in cooperation with
D. in cooperation to

Choose the best answer for the following sentence:
If only I ___________ him now. 
A. see               
B. saw                   
C. have seen                
D. seen

Choose the best answer for the following sentence:
If something is on your __________, you are thinking or worrying about it a lot.
A. mind
B.  brain                    
C. head         
D. hand