This sediment layer is enriched in the rare metal iridium and other elements that are relatively abundant in a meteorite but very rare in the crust of Earth.

这一沉积层富含稀有金属铱，以及其他在陨石中较丰富而在地壳中十分罕见的元素。

youdao

Meningitis is relatively rare but extremely serious and universities advise students to be immunised against meningitis C, following outbreaks on a number of UK campuses in recent years.

脑膜炎是相当罕见而非常严重的疾病。 由于近来年在英国大学里爆发过数起脑膜炎疾病，大学往往建议学生打脑膜炎疫苗以抵抗脑膜炎。

youdao

Personal computers are still relatively rare in India but televisions are ubiquitous.

在印度个人电脑仍较稀少，但电视已相当普及。

youdao

It said pilot whales and sun fish had also made appearances but sightings were relatively rare.

BBC: NEWS | UK | Wales | South West Wales | Killer whales surprise twitchers

But these are still relatively rare and new implementations are very expensive--each handheld radio alone can cost a few thousand dollars.

FORBES: Crisis Communicating

The science team likened its chemistry to some relatively rare but well-studied alkaline rocks on Earth found on oceanic islands such as Hawaii and the Azores, and also in rift zones like the Rio Grande.

BBC: Cosmic coincidence on the road to Glenelg