bury one’s head in the sand.逃避现实
——I lost my job, and I feel blue these days
——Hey，Don't bury your head in the sand. Everyone’s life is filled with ups and downs，pull yourself together.
——我丢了工作，这些天心情很不好。
——Hey，不要逃避现实了。每个人的生命中充满了起起落落，振作起来吧！

come down to earth / come back to earth回到现实，不再幻想
You have a fit of enthusiasm, Tom, but you must come down to earth. We can't possibly afford any of your suggestions.
汤姆，你满怀热情，但请回到现实中来吧。我们或许不能接受你的任何建议。

face the music勇敢地面对困难；接受应得的
I didn’t finish my work, so I have to face the music.
我没做完功课，所以我只得硬着头皮挨训了。