请根据要求改写下列句子，每空一词。
(1)Her father has been on the phone since half an hour ago. （对划线部分提问）
  has her father been on the phone?
(2)I think diving is the most difficult activity of all. （保持句意基本不变）
I think diving is more difficult than   activity.
(3)We can put those machines on the ground floor of the building. （改为被动语态）
Those machines can  on the ground floor of the building.
(4)The beach is a nice place for tourists.  （改为感叹句）
 nice place for tourists the beach is!
(5)Pingping is so energetic that he can be a good monitor. （改为简单句）
Pingping is  to be a good monitor.