lucrative adj. 賺錢的，有利可圖的

　　詞根記憶：lucr+ative賺錢的

　　Burdened by debt, Lydgate abandons his dreams of reforming medicine to take a conventional but lucrative practice in London.

　　advantageous, gainful, profitable, remunerative

　　ludicrous adj. 荒唐可笑的

　　詞根記憶：lud+icrous鬧著玩的可笑的

　　Although his attempts to appear psychotic were so clumsy as to be almost ludicrous , there is evidence that Ezra Pound was able to avoid standing trial for treason merely by faking symptoms of mental illness.

　　laughable, comic, comical, droll, farcical

　　lugubrious adj. 悲哀的;憂郁的

　　Much of the clowns success may be attributed to the contrast between the lugubrious manner he adopts and the general hilarity that characterizes the circus.

　　melancholy, dolesome, dolorous, lamentable, plaintive

　　luminous adj. 發光的;發亮的;光線亮的;明白易懂的;有光澤的

　　詞根記憶：lumin+ous發光的

　　Although supernovas are among the most luminous of cosmic events, these stellar explosions are often hard to detect, either because they are enormously far away or because they are dimmed by intervening dust and gas clouds.