—It is said that Jack is very rich and is always changing his private cars.What is he?—      ,I am not sure.

＿＿＿＿being March 12th, they planted trees on the hill. 

One of the most important problems they had to consider was________of public health.

 Frankly speaking, ________ of them knew what the other was doing that morning.

— We were talking about the new play ____， remember?  — Yes， I enjoyed it very much.