It's extremely rare for it to be this hot in April.

四月份就这样炎热是极其罕见的。

《牛津词典》

This species is extremely rare.

这一物种极为罕见。

《牛津词典》

This combination of qualities is generally supposed to be extremely rare.

一般认为，同时具有这样一些品质极为罕见。

《牛津词典》

He says young dinosaur fossils are extremely rare, a possible sign that many of them had been eaten by attackers.

VOA: special.2009.09.01

Reports of solar system objects striking each other are extremely rare.

VOA: special.2009.08.25

"And to break records by that sort of margin is something which is extremely rare."

VOA: standard.2009.09.03

One replica showroom houses classic and talked-about models, including the 166MM, an extremely rare car from 1953.

BBC: The ultimate Ferrari festival

Meetings with North Korea's leader are extremely rare for foreign leaders except for China.

WSJ: Trip to Pyongyang Irks Tokyo's Allies

Pink diamonds of this size, as regular readers of this blog know, are extremely rare.

FORBES: Connect