太阳缓缓沉入地平线以下，发出红色的光芒。

The sun glowed red as it ___sank slowly below the horizon.

今年学生人数大幅下降。

Student numbers have ___sunk considerably this year.

多拉脸色苍白，瘫坐在椅子上。

Dora's face grew pale and she ___sank into a chair.