My practice 5. The verbs that can be followed by -ing or 'to' with a difference of meaning.
YOU'RE DOING GREAT, I JUST MADE A FEW CORRECTIONS FOR YOU.:
1. The shark tried to bite the swimmer, BUT IT DROWNED ("TO DROWN" CAN BE USED TRANSITIVELY OR INTRANSITIVELY. EXACTLY WHO OR WHAT DOES "IT" REFER TO? IT SEEMS TO REFER TO THE SHARK, BUT SHARKS CANNOT DROWN, CAN THEY? IF THE SWIMMER DROWNED, WE SAY "HE" OR "SHE," BUT HOW WOULD DROWNING SAVE THE SWIMMER FROM BEING BITTEN?
John tries writing (BETTER "IS TRYING TO WRITE") a book about sharks and he believes in his success. (THERE'S NOT CHANGE IN MEANING IN YOUR EXAMPLE).
2. Before the New Year, Russians need to cook the Olivier salad. USUALLY WE DON'T COOK SALADS -- WE PREPARE THEM. WHAT IS OLIVIER SALAD?
This salad needs covering (OR, MORE NATURALLY "NEEDS TO BE COVERED") with mayonnaise. MAYONNAISE IS NON-COUNTABLE.
3. Employees from "WWF" help to protect endangered animals like the nice pandas. HMMM... IS THERE ANOTHER KIND OF PANDA THAT ISN'T NICE?
Unfortunately, without responsibility, people can't help (TO) SAVE the animals and nature (NO ARTICLE FOR "NATURE"). (CAN'T HELP SAVING WOULD MEAN THAT THEIR SAVING THE ANIMALS IS INEVITABLE.) (THERE WAS A CHANGE IN MEANING IN YOUR EXAMPLE, BUT THE MEANING WAS ILLOGICAL).
4. I am afraid to stay HOME ALONE. (BTW, YOU SHOULD WATCH THE MOVIE "HOME ALONE" -- IT'S NOT SCARY AT ALL.)
People ARE often afraid of loosing ("LOSING") their passports, (COMMA) so they don't carry them.
5. I'm interestED in reading English literature.
IT was interesting to know what unused words and phrases were before. (THE GRAMMAR IS REASONABLY CORRECT, HOWEVER, I HAVE NO IDEA WHAT THIS IS SUPPOSED TO MEAN.)
6. My best friend was sorry to hear that I HAD BEEN ILL.
My mom is sorry for making me take pills. (OR "... FOR HAVING MADE ME...")
I HOPE THIS HELPS.. KEEP UP THE GOOD WORK!