If he HADN'T NOTICED the mould in one of his glasses, Alexander Fleming … WOULD HAVE NEVER DISCOVERED penicillin.
If he HAD SOLD some of his paintings, Van Gogh WOULD HAVE GOT some recognition.
If Barbara Streisand HAD CHANGED the shape of her nose, her career … WOULD HAVE NEVER BEEN the same.
If Anne Sullivan HADN'T TAUGHT her, Helen Keller WOULDN'T HAVE BEEN ABLE TO communicate.
If Naomi Campbell WASN'T so beautiful, she WOULD HAVE NEVER BECOME) a super model. ("wasn't" because she is still beautiful)