1.invertebrate n.．无脊椎动物(an animal, such as an insect or a mollusk, that lacks a back- bone or spinal column)

词根记忆：in（无）+vertebrate(脊椎的)--无脊椎的--无脊椎动物

例：In cold-water habitats, certain invertebrates can convert starches into complex carbohydrates.

2.inverted a.反向的，倒转的(reversed)

例：When a pterosaur(翼龙)walked or remained stationary, its wing could only turn upward in an extended inverted V-shape.

同根词：inversely( ad.相反地，倒转地)

3.investigate v.调查（to examine in order to obtain the truth)

联想记忆：invest(投资)+igate--投资前的必要步骤--调查

例：Such studies have neglected to investigate firms that attempt to serve only a narrow target market.

派生词：investigation(n．调查，调查研究)

同根词：investment(n．投资)

4.invoke v.行使（法权等），实行(to implement)

词根记忆：in（进入）+voke(喊，唤)--唤起--突行

注意：revoke(v.废除)

例：invoke the veto in the dispute在辩论中行使否决权

5.involvement n.参与(participation)；牵扯，卷入(be involved in sth.)

词根记忆：来自involve(v.卷入，连累)

例：Greater land rights and greater involvement in trade made women in precolonial Ghana less dependent on men than were European women at that time.

6.irate a．生气的，愤怒的(very angry)

词根记忆：ir（生气，发怒）+ate--生气的，愤怒的

例：irate consumers愤怒的消费者

7.iridescence n.．彩虹色(colors of rainbow)

词根记忆：irid（=iris虹光）+escence--彩虹色

例：Scientists have recently discovered that the ultrathin, layered construction of a butterfly's wings-the same construction that makes some butterflies shimmer via the phenomenon of iridescence-also enables the insect to control how much heat energy is absorbed by its wings and how much is reflected away.

8.ironic a．说反话的，讽刺的(sarcastic)

词根记忆：来自irony(n.反话)

例：an ironic smile冷笑

派生词：ironically( ad.说反话地，讽刺地)

9.irradiate v．照射(to cast rays of light upon)；使明亮，生辉(to shine; to light up)