try/except with conditionals

I am a newbie in programing...... I am trying to solve this problem using try/except and conditionals if/elif/else. I am trying hard, can't find any solution. Please help!!

Write a program to prompt for a score between 0.0 and 1.0. If the score is out of range, print an error. If the score is between 0.0 and 1.0, print a grade using the following table: Score Grade

= 0.9 A = 0.8 B = 0.7 C = 0.6 D < 0.6 F If the user enters a value out of range, print a suitable error message and exit. For the test, enter a score of 0.85.