Số 253125000 có bao nhiêu ước số tự nhiên?
A. 160
B. 240
C. 180
D. 120

Giả sử khi thực hiện một phép chọn nào đó ta phải thực hiện theo phương án A hoặc phương án B. Thực hiện phương án A có m cách khác nhau và phương án B có n cách khác nhau. Khi đó phép chọn được thực hiện theo:
A. m.n cách khác nhau.
B. m + n cách khác nhau.
C. mn cách khác nhau.
D. nm cách khác nhau.

Choose the best answer for the following sentence:
As for me, I consider reading ___________ important part of __________ life. 
A. an / Ø                   
B. the / a               
C. Ø / the                  
D. an / a

Choose the best answer for the following sentence:
A shoe of leather is a _____________________. 
A. leather shoe                
B. shoed leather                  
C. shoe leather              
D. skinned leath

Choose the best answer for the following sentence:
If you ___________ time, please write to me. 
A. have            
B. had               
C. have had          
D. has

Choose the best answer for the following sentence:
She told me that she'd rather ___________ on the committee. 
A. not to serve                   
B. not serving
C. not serve                 
D. serving not

Choose the best answer for the following sentence:
He always prevents me _________ doing my duty.
A. of                
B. from             
C. with                  
D. against

Choose the best answer for the following sentence:
''When _____________?''
“In 1928.” 
A. penicillin was invented                     
B. did penicillin invented
C. was penicillin invented                
D. did penicillin invent

Choose the best answer for the following sentence:
______________ weapons have made more contribution to poaching and killing wild animals. 
A. Huge                 
B. Light                    
C. Advanced                  
D. Commercial

Choose the best answer for the following sentence:
Studying abroad can be very different form studying in your country. For example, in most schools in the UK, ______________ sport is encouraged.
A. join in
B. participation in
C. getting on
D. joining