problem 1 nsdate
problem # 2 NSRrange and NSString
problem # 3 still contains errors
problem # 4
doesn't want to run
some thread error
problem # 6, didn't do 5 because i am totally lost in it
problem # 7  i put everything in the main
Not working, bcuase i can't find the fraction class.
chapter 9
Chapter 11 and chapter 15