It is very difficult to retain all that you hear in the class.
A. keep
B. recall
C. preserve
D. conserve

• preserve i think
• 9 years agoHelpfull: Yes(0) No(0)
• You cannot concerve answer is d
• 9 years agoHelpfull: Yes(0) No(0)
• It should be preserve because conserve is synonyms of preserve and it's meaning is protection.
• 7 years agoHelpfull: Yes(0) No(0)