dead loss
noun [ S ] informal uk/ˌded ˈlɒs/ us/ˌded ˈlɑːs/
无用功，白费力
an activity or process that is not at all effective or successful
Yesterday's meeting was a dead loss - nothing was decided. 昨天的会白开了——什么都没有决定下来。
废物；无用之人
a person who is not successful or useful
I was a dead loss at languages at school. 我上学时对各种语言课程总是一筹莫展。
John was a dead loss - he just stood there and did nothing. 约翰真没用——他干站在那里什么也不干。