21（）

单项选择题When Mary was in hospital, the couple realized that（）

A．they had to put their plan into practice
B．health was more important than wealth
C．heart trouble was a serious illness
D．they both needed to stop working

单项选择题People who fly with Bel Air（）

A．know they will travel a lot
B．get what they want quickly and safely
C．know that everything will be just right
D．always travel around the world