beetroot甜菜根，as red as a beetroot字面意思像甜菜根一样红，引申为满脸通红。

【例句】
He went as red as a beetroot when I asked about his new girl-friend.
我问起他那新女友，他就满脸通红。

I could feel myself going as red as a beetroot when she said that my work had been chosen for the prize.
听她说我的作品评上奖了，我的脸一直红到耳朵根。