in high spirit还是in high spirits

in high spirit还是in high spirits 是in low spirit 还是in high spirits? 英语用法为什么是in high spirits而不是in high spirit in a good mood,in high spirits in good spirits 与in high spirits的区别 in high Christmas spirits什么意思 心情愉快是in high spirits?为什么不是in good spirits in high efficiency还是at high efficiency 是 in high 还是 in height 问：in high还是in height I'm in a high spirits 中间是不是不应该有a? Nawadays,many students are in high spirits at the mere menti