5) These exercises are very long. I can't finish them in an hour.
a. These exercise are so long that i can't finish them in an hour
b. These exercise are too  long for me to do in an hour
c. These exercise are not short enough to finish in an hour
6) She is very old. She can't live by herself.
a. She is so cold that she can't live by herself
b. She is too   old to live by herself
c. She is not young enough to live by herself

5.
a. These exercise are so long that i can't finish them in an hour
b. These exercise are too  long for me to do in an hour
c. These exercise are not short enough to finish in an hour.

6.
a. She is so cold that she can't live by herself
b. She is too   old to live by herself
c. She is not young enough to live by herself