Thanks a lot. I have visualized the codeexecution step by step and Now I have undrerstood what I have been doing wrong. Tha solution for this kata is corrected. All test passed. Tahnks once again.

You dont need to paste your solution here because we know it is not right, and we know what is wrong with it. Run your solution in your PyCharm twice, like this:

print(is_pangram(" bcdefghijklmnopqrstuvwxyz"))
print(is_pangram("abcdefghijklmnopqrstuvwxy "))

and see what is the result. (edit: fixed the example)

Mayby I will paste here my soution and you will tell me is it right?

Yes, because you only run one test at once. Try running a test which expects True and directly afterwards (next code line) a test which expects False.

Test Results:
Fixed tests
Test pangrams
Test Passed
Test Passed
Test Passed
Test Passed
Test Passed
Test non-pangrams
Incorrect answer for 'This isn't a pangram!': True should equal False
Incorrect answer for 'abcdefghijklm opqrstuvwxyz': True should equal False
Incorrect answer for 'Aacdefghijklmnopqrstuvwxyz': True should equal False
However whan I run this function on Pycharm the output for "Test non-pangrams" is as it should be - False

Your solution will not work when run twice in a row.

is your code failing all the tests?