1. Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate.
【译文】和世界上大多数火山不同的是，它们并不总是在构成地球表面的巨大漂流板块之间的边界上出现；相反，许多热点处于板块较深的内部。
【析句】这是一个由两个分句组成的并列句，中间由分号隔开。在前一个分句中， Unlike most of the world’s volcanoes是一个形容词短语，修饰句子的主语they。定语从句（that make up the earth’s surface）修饰the great drifting plates。第二个分句结构较简单，注意many of them是指many of the hot spots。
【讲词】make up意为“化妆；补足；拼凑；组成；编造”等。He made up an excuse for his absence in class, which was found out.（他编了一个借口没来上课，结果被发现了。）I’ll make up the difference in the bill.（我来补上帐单的差额。）You have to make up the lost time by studying harder.（你应该更加努力学习，以弥补失去的时间。）He kissed his wife and made up with her.（他吻了妻子，和她和好了。）
2. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined.
【译文】 互相吻合的海岸线和某些似乎跨越海洋的地质特征会使人想到这两个大陆曾经是连在一起的。
【析句】 这个单句的主语是the complementary coastlines and certain geological features，后面跟了一个定语从句（that seem to span the ocean），从句中that充当的是主语。全句的表语名词reminders跟了一个of短语结构，其中包含一个表示地点的从句。
【讲词】 reminder的意思是“暗示；有提醒作用的人或物”。The museum serves as a reminder of the crimes committed against the people of Nanjing.（纪念馆提醒人们不要忘记南京人民所遭受的暴行。）
span作名词表示“跨度；范围”，作动词时意为“横越”。Richard Carleton, an award-winning journalist whose career in Australian television spanned 40 years, died on Sunday.（理查德·卡尔顿星期天去世，这位多次获奖的记者曾在澳大利亚的电视机构工作了40年。）The Thames is spanned by many bridges. （泰晤士河上架设了许多桥梁。）