1. 表述法：fifth wheel
释义：An unwelcome or extra person. （多余的人）
例句：I didn't realize that the party was for couples only, so when I showed up alone, I felt like a fifth wheel.
I don't like living with my son and daughter-in-law. I feel like a fifth wheel.
Bill always begs to come on camping trips with us, but really, he's a fifth wheel.
A: Did you have a good time at the party?
B: Not really. Since my girlfriend didn’t come, I was a fifth wheel at the party.
2. 表述法：third wheel
释义：Someone who has no real place or purpose in a situation. （累赘，电灯泡）
例句：When Kelly invited me to go to the movies, I didn't know that her boyfriend would be joining us. I felt like a third wheel the entire night.
You two go ahead. I do not want to be a third wheel.
I know that you are not trying be rude, but sometimes I feel left out, like a third wheel.
3. 表述：take the fifth
释义：To refuse to answer a question or provide information. （保持缄默，避而不答）
例句：The defendant took the fifth after every question the prosecution put to him.
Just take the fifth if your mom asks where you've been all night!
Don’t ask me! I’ll take the fifth on that one. Go and ssk Fred.