It is difficult to ride a horse. (Correct)

• This sentence is already correct. It expresses that riding a horse is challenging.

She is so happy to see a member of the football team.

• We've rearranged the words to form a clear and meaningful sentence.

I am relieved to hear he successfully finished the race.

• "I am" is added as the subject, and the words are rearranged to form a complete sentence expressing relief.

Nick must be proud to be the only winner of the game.

• "Must be" is used to express a strong assumption or belief.

It is dangerous to windsurf if you don't know how to swim.

• This sentence emphasizes the danger of windsurfing without swimming skills.

It is silly to have a bath in such cold weather.

• This sentence expresses the absurdity of taking a bath in cold weather.

It is fun to ski in the winter.

• This sentence simply states that skiing in winter is enjoyable.

It is safer to wear a helmet when you play hockey.

• This sentence highlights the safety benefits of wearing a helmet while playing hockey.