Corrected sentence (simple):
The Arctic fox moults to stay warm in winter and to be invisible in summer.
Better, clearer version:
The Arctic fox moults to stay warm in winter and to blend in with its surroundings in summer.
Why we changed it (step by step):
- The original sentence left out a word and sounded uneven. It said: "...to stay warm in winter and invisible in summer."
- We need the same grammatical pattern for both parts: "to stay" and "to be invisible". That makes the sentence balanced. So we add "to be" before "invisible."
- "Invisible" can sound like magic. A clearer word for kids is "blend in" or "camouflaged," because the fox's fur changes color so it mixes with the snow or rocks.
- Note: "moults" is British spelling. In American English people write "molts." Both are okay.
If you want two short sentences for clarity:
In winter, the Arctic fox grows thick fur to stay warm. In summer, it sheds fur so it blends in with the ground.