To have a face like thunder:
臉(liǎn)像打雷一樣(yàng) ×
火冒三丈 √
例句 ：
He had a face like thunder when he came out of the manager's office this morning.
他今天早上從(cóng)經理辦(bàn)公室出來的時候滿臉怒氣 。
To chase the rainbows:
追逐彩虹 ×
癡(chī)人說夢(mèng) √
例句：
You have only started two months ago, you are already thinking about promotion. Well, I think you're just chasing rainbows.
你才來瞭(le)兩個月就想著(zhe)升職的事情瞭(le)，我看啊，你是淨想好事兒呢。
Rainy day:
① 雨天
② 窮(qióng)困時(shí)期 √
例句：
I'll put the rest in the bank for a rainy day.
我要把餘款存入銀行以備不時之需。
（内容來自學英語口語，如有侵權請聯系删除）
