im-，in-(加在字母m，b，p之前)not，in，into否定，加强或引申意义
impracticable行不通的
E.g.Such measures would be highly impracticable and almost impossible to apply.
这样的措施非常不切实际,几乎不可能付诸实施。
invisible不可见的;
E.g.Parents fear they might overstep these invisible boundaries.
父母担心他们可能会逾越这些无形的界限。
irrational不合理的;
E.g. His behavior was becoming increasingly irrational.
他的行为变得越来越不理智了。
5. mal- bad，badly：恶，不良
maltreat虐待;
E.g.He said that he was not tortured or maltreated during his detention.
他说自己在押期间并未遭受拷问和虐待。
malnutrition营养不良
E.g.Infections are more likely in those suffering from malnutrition.
营养不良的人更有可能被传染。
