1.〈非正式〉难得;罕见;千载难逢
1.<informal>very rarely
1.How can you let such a golden opportunity to make big money slip through your fingers? It was an opportunity that comes once in a blue moon.
这样一个发大财的机会千载难逢，你怎么能眼睁睁地让它溜掉呢。
2.In recent years, we don't often get a chance to visit our grandparents. They live so far away. We get to see them once in a blue moon.
最近几年，我们很少有机会去看望祖父母。他们住的太远了，见一面真有千载难逢之感。
3.His parents are very strict with him and allow him to go out with his pals in the evening only once in a blue moon.
他的父母亲对他很严格，难得准许他和朋友们在晚上一起出去。
4.Sally: Wow, this is really a chance once in a blue moon. Please invite me to go with you!
哇，这真是千载难逢的好机会。求求你邀请我跟你一起去嘛！
5.He is not very keen on swimming. Only once in a blue moon do we meet him in the swimming pool.
他不喜欢游泳，我们很难得在游泳池遇到他。
6.Since our parents live so far away, in recent year we get to see them once in a blue moon.
因为父母住在远处，所以我们近来很少和他们见面。
7.Since our parents live so far away, recently we get to see them once in a blue moon.
因为父母住得比较远，所以我们近来很少和他们见面。
8.Don't give up a such a good opportunity; it only comes once in a blue moon.
不要放弃这个好机会；那是非常难得的。）（当副词用）
9.And he said that only once in a blue moon does a dog's ear grow back.
而且他还说除非天下红雨狗才会再长出耳朵来的
10.The most famous actors of the day. But chances like this happen once in a blue moon !
但是象这样的机会发生在蓝色的月球也仅一次！