crowded

The subway train was so crowded during rush hour that I couldn't even move my arms.

(Chinese) 高峰时段地铁里非常拥挤，我连手臂都动不了。

Small, crowded classrooms can make it difficult for students to concentrate on lessons.

(Chinese) 狭小、拥挤的教室会让学生难以集中注意力听课。