根据句意，用所给单词的适当形式填空。

小题1:We all know ______________ (pollute) water does harm to our health.

小题2:I have read five                  (twelve) of this book.

小题3:If you are in a blue mood, you can do your hobbies to cheer                ( you) up, boys.

小题4:To tell you the                 (true), I felt sad while you were away. 

小题5:The children heard the                 (frighten) shout and looked at each other in fear.

2015年是十二五收官之年，关于十二五时期我国取得的成就说法错误的是（）。

A.国内生产总值年均增长7.8%

B.成为全球第二货物贸易大国

C.经济总量稳居世界第二位

D.服务业成为第一大产业