The reason________the president kept silent is still unknown.

• A、how

• B、why
  

• C、when 
  

• D、what

There is nobody here in the office, they________have all gone home.

• A、can
  

• B、must
  

• C、should
  

• D、would

P: I’m running a fever. I’ve caught a cold.
S: Oh, _____54_____?