ice age

period when much of the northern hemisphere was covered with glaciers 冰期; 冰川期; 冰河时代.

I (also i), I'd, I'll, I'm, I've, I, i, i. e., I.D. card, i.e., I.Q., i/c, iambic, iambus, IBA, ibex, ibidem, ibis, IBM, ICBM, ice, ice cream, ice crevasse, ice dancing, ice hockey (US hockey), ice lolly (US Popsicle), ice-axe (also esp US ice-ax), ice-blue, ice-bound, ice-breaker, ice-cap, ice-cold, ice-cream, ice-cube, ice-fall, ice-field, ice-floe, ice-free, ice-pack, ice-pick, ice-rink,