Phương trình lượng giác ${{\cos }^{2}}\,x+2\cos x-3=0$ có nghiệm là 
A. $\displaystyle x=k2\pi .$ 
B. $\displaystyle \text{x}=0$ 
C. $\displaystyle \text{x}=\frac{\pi }{2}+k2\pi $ 
D. Vô nghiệm.

Nghiệm của phương trình cosx + sinx = 0 là
A.    
B.     
C.   
D.

 Hàm số đồng biến trên khoảng $\left( \frac{\pi }{2};\pi \right)$ là
A. $y=\sin x.$
B. $y=\cos x.$
C. $y=\tan x.$
D. $y=\cot x.$

Choose the best answer for the following sentence:
She is not ____________ with her position. 
A. satisfying            
B. satisfaction  
C. satisfactory  
D. satisfied

Choose the best answer for the following sentence:
The attendance _________ this meeting is very large.  
A. for 
B. in  
C. at  
D. to

Choose the best answer for the following sentence:
You _________ reserve a hotel room now if you want to be able to get a good rate. 
A. better to               
B. had to
C. had better to                
D. had better

Choose the best answer for the following sentence:
People enjoy a book __________ different ways. 
A. on                  
B. with                  
C. upon                 
D. in

Choose the best answer for the following sentence:
I’d like to visit Lock Ness to see the monster, ______________ it’s too far to go.
A. although 
B. even though
C. but 
D. despite

Choose the best answer for the following sentence:
Many people do not like scuba diving _______________. 
A. because it is dangerous                        
B. because of it is dangerous  
C. because its danger                        
D. due to it is dangerous

Choose the best answer for the following sentence:
 In such a bad situation, you should _____________ of hiring a lawyer.
 
A. desire a chance
B. consider the possibility
C. see the need
D. take advantage