假如说某人 has a yellow streak1, 那意思就是此人比较胆怯、不勇敢。
例句
We went rock climbing at the weekend. I loved it, but my friend refused to try it. Hes got a real yellow streak.
The public accused2 the government minister of having a yellow streak after he refused to answer some difficult questions.
请注意
假如一个人 has a mean streak, 那此人会常常做出卑劣、尖酸刻薄的事情。
My boss wont give me a pay rise - hes got a real mean streak.