Your stomach sinks, you have that sinking feeling in the pit of your stomach, when you get a bad grade on a test.

当你考试考砸的时候,你的胃会垂下去,或者说,会有胃部下垂的感觉

耶鲁公开课 - 死亡课程节选

I've got a really bad grade on my test.

我在一门测试中考了一个很差的成绩。

I'm sure 实战 - SpeakingMax英语口语达人