The unrest has cast a pall over what is usually a day of national rejoicing
动荡的局势给往常举国欢庆的日子蒙上了阴影。

2.throw in the towel 承认失败，认输

We're never going to persuade them so we might as well throw in the towel now.
我们决不会说服他们，因此我们不妨现在就认输