I listened to Dr. Johnson’s lecture about biology, but I failed to get its key ____.

  A. words B. notes C. messages D. points

I listened to Dr. Johnson’s lecture about biology, but I failed to get its key ____.

1. A.
   words
2. B.
   notes
3. C.
   messages
4. D.
   points

I listened to Dr. Johnson's lecture about biology, but I failed to get its ________.

1. A.
   points
2. B.
   words
3. C.
   message
4. D.
   information

I listened to Dr. Johnson's lecture about biology, but I failed to get its ________.

[　　]

I listened to Dr Johnson's lecture about biology, but I failed to get its key _____.

[　　]

A．words　　　B．points

C．notes　　　 D．message