keep flat的用法和樣例：
例句
- Sit back in a comfortable chair, feet flat upon the ground and uncrossed.
坐在一張舒適的椅子上，雙腳平放在地面上，不交叉。 - The plumed tail is one of the characteristics of the breed, and lies flat and straight on the back.
羽毛狀尾巴是這一品種的特徵之一，直直地平放在背後。 - Sit back in a comfortable chair, feet flat upon the ground and uncrossed.
坐在一張舒適的椅子上，雙腳平放在地面上，不交叉。 - The plumed tail is one of the characteristics of the breed, and lies flat and straight on the back.
羽毛狀尾巴是這一品種的特徵之一，直直地平放在背後。
