1+3模型是我指导GRE作文的核心工具之一。按照这个模型,主旨句应该概括后文出现的三个分论点,而中间段的首句则要引出这三个点。在点评习作时,我会检查学生有没有做到这一点。其实对thesis statement和topic sentence的要求不是我发明的,而已经成为美国英语写作教学的传统。早在Strunk and White的Elements of Style里就有这样的建议:
As a rule, begin each paragraph with a topic sentence; end it in conformity with the beginning.
Again, the object is to aid the reader. The practice here recommended enables him to discover the purpose of each paragraph as he begins to read it, and to retain the purpose in mind as he ends it. For this reason, the most generally useful kind of paragraph, particularly in exposition and argument, is that in which
the topic sentence comes at or near the beginning;
the succeeding sentences explain or establish or develop the statement made in the topic sentence; and
the final sentence either emphasizes the thought of the topic sentence or states some important consequence.