down the drain白白浪费
Informal expression describing wasted time or money.
We invested two years and a lot of money into our new invention, but it never worked properly, and now we feel that our efforts were all down the drain.
我们在新发明上花了两年时间,投入了大量资金,但这个发明无法正常运行,现在,我们的努力全都白费了。