My sister's athletic performances after seeing an insect
My sister has always been afraid of insects. It never stopped us from going camping, and it was sometimes amusing to see how fast she could run away. She could easily win a 100-meter race if she was chased by an unidentified flying object. Obviously/Of course/It goes without saying that, she would scream and shake/wave her arms while running. If ever you heard someone crying out in the shower rooms, you could be sure it <em>(a typo I imagine)</em> was her, after seeing/having seen a moth. If you happened to see an agitated shadow inside a/the(?) tent at night, you could be sure it was her, desperately trying to kill the last mosquito. The only problem was the fact that she didn't care about/pay attention to/take heed of whatever was in front of her while/when running. It could be grass/lawn/an open field, a national road/highway/freeway or an abyss, she would run regardless. My parents are now too old to go camping, and it might be safer for my sister's life if they cease/refrain!
<em>Nothing requiring correction, some alternatives and suggestions</em>
My sister's athletic performances after seeing an insect
My sister has always been afraid of insects. It never stopped us from going camping, and it was sometimes amusing to see how fast she could run away. She could easily win a 100-meter race if she was chased by an unidentified flying object. Obviously, she would scream and shake her arms while running. If you heard someone crying out in the shower rooms, you could be sure is it was her, after seeing a moth. If you happened to see an agitated shadow inside a tent at night, you could be sure it was her, desperately trying to kill the last mosquito. The only problem was the fact that she didn't care about what was in front of her when she ran while running. It could be grass, a national road or an abyss, she would run. My parents are now too old to go camping, and it might be safer for my sister's life!
Perfect English! I can't find a single thing to correct (other than when you used "is" instead of "it" in the sentence about "if you heard someone crying out in the shower rooms," but I'm sure that was just a typing mistake). To make it sound a tiny bit more like a native speaker, I might suggest you take out the word "about" and change the words "while running" to "when she ran" in the sentence: "The only problem was the fact that she didn't care about what was in front of her when she ran while running." But that's just a *maybe* correction. It's really excellent the way it is. Great job! And it was a very cute story.