ir-

名词 ir-:

1. a heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium
   同义词：iridium, Ir, atomic number 77
2. a board of the British government that administers and collects major direct taxes
   同义词：Inland Revenue, IR

1. It's the in-thing to do at the moment.
   这是目前最时兴的做法了。