My son asked me to come help at his school track meet but I felt like a fifth wheel when I got there: they already had enough people to help so I just stood there feeling useless.

我的儿子要我在他学校开运动会的时候去帮忙。可是，我到了那里觉得自己似乎是多余的，因为他们已经有好多人在帮忙，我只好站在那里没事干。

youdao

My feeling was that it was useless to argue with him.

我感觉和他争辩是不会有用的。

youdao

I told her I was feeling pretty old and useless that day.

那天我还告诉她我感到自己如此老迈无用。

youdao

With the growing popularity many other attractive features were included in Facebook, thus many started feeling that their Orkut account is useless and deleted their accounts.

FORBES: Facebook Surpasses Orkut, Owned by Google, In Numbers of Users in Brazil