___  I could not remember the text .  [     ]
A. However hard did I try    
B. However hard I tried  
C. However I tried          
D. However had I tried hard

Small boats can easily turn over in the river      they are not managed carefully. [     ]
A. though
B. until
C. if
D. before

No matter _____ great progress you have made in your studies, you should continue to work hard.[     ]
A. what        
B. how      
C. where      
D. when

I could feel my heart beating quickly _____I went on stage to give a lecture. [     ]
A. a long time
B. the first time
C. by a time
D. in no time

_____thirsty I am, I never seem to be able to finish the large bottle of Cola placed before me.[     ]
A. Whatever
B. Whenever  
C. Wherever
D. However