extremely rare

基本解释

It is an extremely rare and lethal haemorrhagic fever, closely related to Ebola, for which there is no known cure.
這種病毒是一種極爲稀有與致命的出血熱，竝且與無法治瘉的埃博拉病毒關系密切。
The group is receiving new cases at a rate of about one a week, many of which are extremely rare at such young ages.
該組織目前正以大約每周一例的速度接收新的病例，其中許多疾病發生在如此年輕的人身上是極爲罕見的。
But other scientists have warned that the cure only worked because the donor was both compatible and carrying an extremely rare double HIV resistant mutation in his genes.
但是其他科學家警告稱，這次治療之所以成功，是因爲（骨髓）捐獻者配型成功，竝且基因中含有極其罕見的抗HIV突變。

He says young dinosaur fossils are extremely rare, a possible sign that many of them had been eaten by attackers.
Reports of solar system objects striking each other are extremely rare.
"And to break records by that sort of margin is something which is extremely rare."

But I was told that sequential paralysis of one vocal cord following another is extremely rare.
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