Mr. Smith didn’t understand _____ made his son so upset that evening.

  A. what was it        B. why it was this  C. how that was     D. what it was that

Mr. Smith didn’t understand _____ made his son so upset this evening.

   A. what was it   B. why it was this  C. how that was D. what it was that

Mr. Smith didn’t understand _____ made his son so upset that evening.

Mr．Smith didn’t understand ________ made his son so upset that evening．

1. A.
   what was it
2. B.
   why it was this
3. C.
   how that was
4. D.
   what it was that