Choose the best answer for the following sentence:
Trees won’t grow __________ there is enough water.  
A. if           
B. when            
C. unless               
D.  as

Choose the best answer for the following sentence:
They were fortunate _________________ from the fire before the building collapsed.
A. rescuing           
B.  to have rescued 
C. to rescue                
D. to have been rescued

Choose the best answer for the following sentence:
Her ___________ was then terrible, and she could have hidden herself in a tomb.
A. elation                       
B. recovery                    
C. depression                         
D. encouragement

Choose the best answer for the following sentence:
If it _________ tomorrow, we may postpone going on a picnic. 
A. rains                
B. will rain               
C. shall rain              
D. raining

Choose the best answer for the following sentence:
The next meeting ________________ in May. 
A. will hold                          
B. will be held                          
C. will be holding                        
D. will have held

Choose the best answer for the following sentence:
The village representative _______________ the villagers to repair roads and plant trees.
 
A. promised the volunteer to help             
B. apologized the volunteers for helping       
C. ordered the volunteers for helping                  
D. thanked the volunteer for helping

Choose the best answer for the following sentence:
The exam is coming, so I’m _______ a lot of study pressure.
A. with
B. under
C. of
D. in

Với f(x)=1-3x+x2x-1 . Tập nghiệm của BPT f'(x)>0 là:
A. R
B. ∅
C. (1; +∞)
D. R\{1}

Cho hàm số . Hệ thức liên hệ giữa y và y” là:
A. y” + 4y = 0
B. y” - 2y = 0
C. y” - 2(y - 1)3 = 0
D. y” + 4(y + 2)2 = 0

Cho hàm số . Phương trình f'(x) = f(x) có tập nghiệm là:
A. {0 ; 1}
B. {- ; }
C. {2 ; 3}
D. Một tập khác.