An endangered species is the one _________ population is so small that it is in danger of becoming extinct.

A. enough intelligent  

B. to pass                   

C. economics              

D. help

A. Ways of teaching                                  

B. Ways of giving assignments

C. Ways of using the textbook                   

D. Ways of taking an exam

A. hadn’t been invited                      

B. not have been invited

C. haven’t been invited                              

D. not be invited

A. are arriving            

B. have arrived           

C. has arrived             

D. is arriving

A. single         

B. scarce        

C. lonely        

D. unique

A. To be successful on the Internet            

B. Support from Youniversity Ventures

C. Sharing Success on the Internet             

D. The best videos from YouTube

A. Very often it’s to get a better job           

B. All of them are

D. I heard it was very good