quad sense amplifier

例句：

1. 1. The quadrant of the sky is filled with stars.
   天空的这个角落充满了星星。
2. 2. The quadrangle was once a bustling market.
   这个四边形曾经是一个繁忙的市场。
3. 3. The quadrangle is surrounded by trees and fields.
   这个四边形被树木和田野包围着。