1997 Math Challenge

This is a grade 6, all year, challenge, however, the grade 7's may want to try it too!

"1997"

Using ALL four and ONLY the four digits 1, 9, 9, and 7 each time, form expressions for all the numbers from 1 to 100.  You may use

+, -, x, ÷, and ( ).

If you find an expression that works, bring it to school and put it up on our class poster.  Be sure to initial your work so you get credit!  Have fun!