rare and

基本解释

This is pretty rare and is usually found only in large organizations.
这种方法很少见，通常只是在大型组织中看到。
However, promotions are rare and must be earned rather than demanded.
可是，晋升是很少，而且是可挣而不可要求的。
The sample size is of course very small, with specimens rare and samples for experimentation rarer.
样本当然非常小，因为标本很少而能用来做实验的样本就更少了。

Because his wife Millicent liked to invite her friends to big dinners and serve them rare and expensive food and wine.
These cells are rare and so it's been hard to identify them, that's part of it.
这些细胞太少了,所以很难找到,这是原因之一
耶鲁公开课 - 生物医学工程探索课程节选
You have a full monarchy in the sense that both-- we in America talk about the separation of church and state, that is a very rare and unusual thing in the history of the world.
他有一个完全政教合一的君主政权,在美国政教是分离的,这在世界历史上很少见
耶鲁公开课 - 古希腊历史简介课程节选

Problems are rare and if something ever came up Amy got it resolved with customer service.
FORBES: How Amy Promotes This Old House