In the following pairs of sentences, a, b or both are correct. Put a cross (X) next to every
sentence that is incorrect. Write the correction. 
Example: 
a) Drop a line when you get there. 
b) He was upset to discover he dropped from the team. (X) (had been/ was dropped) 
 1- 
a Inflation was increased over the last six
months. X (has increased) 
b My salary was increased by just over 5 percent. (correct) 
 2- 
a They have expanded production facilities at the
Old factory. (correct)
 b Metal is expanded when heated. X (expands) 
 * I understand -Metal expands when heated- is correct because it is an ergative verb. But why -Metal is expanded when heated- is wrong? 
 * I also understand -Inflation has increased by just over 50 percent- is right. But why -Inflation was increased over the last six months.- is wrong?
Thanks in advance!