1.irradiation n．放射，照射(the act of exposing to radiation or the condition of being so exposed)
词根记忆：ir+radi(光线，辐射)+ation--辐射开去--放射，照射
例:microwave irradiations微波照射
2.irreconcilable a．矛盾的，不能协调的(impossible to reconcile)
词根记忆：ir（不）+reconcilable(可调和的)--不能协调的
例：The goals of the two approaches began to seem increasingly irreconcilable.
3.irregularity n．不规则：无规律：不整齐(the quality or state of being irregular)
词根记忆：ir（不）+regular(规则的)+rty(名词)--不规则
例：According to one expert, the cause of genetic irregularities in many breeds of dog is not so much that dogs are being bred for looks or to meet other narrow criteria as that the breeds have relatively few founding members.
4.irreversible a．不可改变的(impossible to reverse)
词根记忆：ir（不）+reversible(可改变的)--不可改变的
例：Continued use of fossil fuels will cause an irreversible shift in earths climatic pattern.
派生词：irreversibility(n.不可改变性)；irreversibly( ad.不可改变地)
5.irrigation n.灌溉(the watering of land by artificial means to foster plant growth)
词根记忆：来自irrigate(v.灌溉)
例：Because of new government restrictions on the use of Davison River water for irrigation, per acre yields for winter wheat, though not for spring wheat, would be much lower than average.
6.irritant n.刺激物(stimulus)
词根记忆：ir+rit(刺激)+ant--刺激物
例：chemical irritant他学刺激物
7.irritating a．刺激的(irritative )；使人愤怒的，气人的(annoying)
词根记忆：来自irritate(v.刺激：使恼怒)
例：Unlike cigarette tobacco, which yields an acid smoke, pipe tobacco, cured by age-old methods, yields an alkaline smoke too irritating to be drawn into the lungs.
同根词：irritative (a．刺激的)
8.islet n.小岛(a small island)
例：Even tiny islets can be the basis for claims to the fisheries and oil fields of large sea areas under provisions of the new maritime code.
1.isolate v.使孤立(to set apart from others)：隔离(to segregate)；a．孤立的(being alone)
词根记忆：i+sol(单独)+ate--使单独--孤立
例：Domestic work tended to isolate women from one another.
派生词：isolated(a．隔离的；孤立的)；isolation(n．隔离：孤立)