exit ramp的用法和樣例：
例句
- A highway interchange at which two highways, one crossing over the other, have a series of entrance and exit ramps resembling the outline of a four-leaf clover and enabling vehicles to proceed in either direction on either highway.
苜蓿葉式立體交叉的公路兩條高速公路的立體交叉道，一條穿過(guò)另一條，有一系列入口和出口坡道，與四葉苜蓿的外形相似，車(chē)輛在兩條高速公路上均可駛入任一的兩個(gè)方向
