ions is not clear. In this study we asked the questions: Do shoot sections remain viable and, if so, are they capable of further growth? We also examined the effect of habitat history and section length on survivorship.
如果一项研究、一篇论文不止一个目的，应该按目的的主次排列顺序，并用连接词或词组。
例28
The present work extends the use of the last model to asymmetric, body-vortex cases, thus increasing the range of flow patterns that can be investigated. In addition, an effort is made to improve the numerical procedure to accelerate the convergence of the iterative solution and to get a better rollup of the vortex lines representing the wake.
常见的连接词还有additionally, in addition to this, besides this, also, not only…but also…, further, furthermore, moreover 等
8.5 如何写引言的结尾
研究目的完全可以作为引言的结尾。也可以简单介绍一下文章的结构及每一部分的主要内容，从而起到画龙点睛的作用，使读者了解文章的轮廓和脉络。
至于研究结果，在引言中完全可以不写。研究结果是结论部分最主要的组成部分。例29是引言的结尾，介绍文章的结构。
例29
…Before examining in detail the optimum control strategy for the drivetrain, Section 2 defines the hybrid arrangement under study. A description of the optimization process using an appropriate cost function is then presented in Section 3 followed by a method of translating the resulting control structure into a sub-optimum algorithm capable of being implemented in real time. Using the optimum control structure the effect of component ratings on the vehicle's performance is evaluated in Section 4, while Section 5 discusses the practical implementation of an overall vehicle control algorithm. Finally, in Section 6, an indication of the vehicle's potential for substituting petroleum fuel by electricity is given.
在介绍全文的结构时，要避免使用同一个句型结构，如，Sections l describes…Section2　analyses…Section3　discusses…Section 4 summarizes…这样，每句话用同样的词开头，句型结构显得单调、枯燥乏味。
思考题
一、根据引言的结构规律排列次序。
1. A national assessment of water quality training needs for extension staff identified drinking water as a nation-wide concern (Bergsrud et al. 1990). According to the study, many county agents were concerned with the health risks of drinking water contaminants and the effectiveness of water treatment devices. But, as the assessment showed, most county agents felt ill-equipped to conduct proactive educational programs in drinking water quality.
2. The objectives of this project were to use a distance education training program to teach county extension agents (1)water quality and supply management principles and (2)how to use educational materials to teach water supply management to others. The expectation was that, once trained, extension agents would begin to reach out to the hundreds of thousands of Ohioans who might benefit from education in water supply management.
3. For decades, the Cooperative Extension System has conducted outreach educational programs for US citizens as a part of the land grant university system. Rural residents often perceive the county extension agent as the most familiar member of the Extension System. With offices in nearly every county in the country, extension agents have traditionally conducted educational programs for adults and youth in topics related to agriculture, home, and family. In the 1980s Cooperative Extension began a new national water quality initiative (Bergsrud et al. 1990). More than 95% of the nation's rural residents depend on groundwater as the major source of water supply. Teaching rural Americans about water quality issues presents both challenge and an opportunity for extension.
4. In Ohio, over 750,000 households (19%) rely on private individual water supplies (US Department of Commerce 1983). In these private water supplies the homeowner or farmer is responsible for providing high quality water for their family and livestock. Unfortunately, few educational opportunities exit to teach farmers and rural homeow

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