A long low area between hills or mountains

• Often with a river flowing along its floor

位于丘陵或山脉之间的狭长低地

• 底部常有河流穿行

The internal angle where two sloping roof planes meet

• A channel there that carries rainwater off the roof

两片斜屋面相交形成的内角

• 沿该内角汇集并排走雨水的沟槽

To form or cut into a valley shape

• To erode so that a valley develops

使呈现谷地的形状

• 侵蚀或切割成山谷