for a rainy day:
以防不时之需
1.Keep somthing for a rainy day.
末雨绸缪.
2.She saved money for a rainy day.
她存钱以备不时之需.
3.Save some money for a rainy day.
未雨绸缪；居安要思危.
as right as rain:
完全正常
一切顺利
完全令人满意
1.Jane's been ill,but she's as right as rain now.
简曾患过病,但她现在身体极好.
2.Jane have a cold,but she's as right as rain now.
珍得了感冒,可是她现在完全好了.
3.I wasn't all well yesterday,but I feel as right as rain today.
昨天我很不舒服,但今天感到完全好了.