Big cities are usually c_______ in the main streets.There are people here and there.

问题描述:

Big cities are usually c_______ in the main streets.There are people here and there.

crowded

crowding 拥挤的。应该不能用crowded,因为不是过去式啊,是时时在发生的事啊,所以就用现在时就行,而,它是动词前面又有are 作为be动词,那它应该加ing

crowded 拥挤的
祝你学习进步,更上一层楼! (*^__^*)
不明白的再问哟,请及时采纳,多谢