다음 글의 밑줄 친 부분 중, 어법상 틀린 것은? [3점]
gravitation is the universal attraction between two objects that ①causes them to pull toward each other. the more mass, or amount of material, an object has, ②the stronger its gravitational force. the pull between objects that are close together is stronger than ③they would be if the same objects were farther apart. the earth’s gravity pulls everything on or near the planet toward its center. our feet remain firmly on the earth even though our planet is spinning on its axis. without gravity, the atmosphere, the ocean, and everything else on the earth ④would fly into space. effects of the earth’s gravity are easy ⑤to see around us. if a flowerpot is knocked from its shelf, it does not sail away. it falls to the floor.

이 문제인데요. 이거 몇번이 틀린건지 자세히 좀 설명해주실수있을까요?
그리고 맞는 번호들도 어떤 문법인지 자세히 설명좀 해주시면 정말 감사하겠습니다.