③withdraw (撤回)

　　1)the plane gradually out of sight. (飞机渐渐远去看不见了。)

　　2)the memory was receding and he couldn`t remember anything. (记忆在变得模糊，他什么也想不起来了。)

　　3)he receded from his promise. (他背弃了自己的诺言。)

　　4)the article receded from the newspaper. (这篇文章从报纸上撤下了。)

　　请注意区别recede和secede。

　　secede vi. withdraw formally from membership in a group， association， organization， etc.; to break off one`s connection with others， as in a political or religious group (从宗教、政党、联盟等组织中退出，脱离)

　　1)nine states seceded from the union government and established their own confederate government。

　　(九个州脱离联邦政府，成立了自己的邦联政府。)

　　2)they seceded from the eec. (他们从欧洲经济共同体中退出。)

　　15.pharmaceutical adj. 药物的，药学的 n. 药品

　　请看下面几个单词，对记忆和理解pharmaceutical会有帮助。

　　pharmacy 药学 　　　　pharmaceutics 制药学

　　pharmacology 药理学 　　　 pharmaceutist 药剂师

　　16.derive v. 由…得到;起源，由…派生

　　1)they derive enormous pleasure from reading. (他们从阅读中得到了极大的乐趣。)

　　2)he said he derived no real satisfaction from his work. (他说他从工作中得不到真正的满足。)

　　3)this word is derived from latin. (这个单词从拉丁语派生而来。)

　　4)electric power can be derived from the sun-warmed surface waters of the ocean。(电力可以从晒热的海洋水面获得。)

　　17.senseless adj. 无知觉的;愚蠢的，无意义的

　　1)he fell senseless to the ground. (他昏倒在地。)

　　2)it was a senseless thing to do so. (这样做毫无意义。)

　　3)he put forward some senseless proposals at the meeting. (他在会上提出了几个愚蠢的建议。)

　　18.overpopulated adj. 人口过密的

　　over-是一个前缀，意思是too much (过度，太过)，如：overcrowd (过度，拥挤)，overdo (过度烹煮)，overeat (吃得过多)，overestimate (估计过高)等等。

　　popul是个词根，意思是people (人)，如：populous (人口稠密的)，depopulation (人口减少)，populace (大众)等等。