3 above) and which ones should go in the literature review which comes later in the Introduction? If the fi ndings are well-known and considered reliable enough to be presented as truths, you can present them in the Present Simple as part of the factual background to your paper (as in Sentence 3) with a research reference. Th e literature review, which describes recent and current research in your fi eld, usually mentions authors by name, and the sentences are usually in the Simple Past or Present Perfect tense. 3. What order should I mention them in? Who comes fi rst and who comes last? Th ese questions about the literature review itself will be discussed aft er Sentence 6. In Sentence 4 'However, it has been found to be too weak under impact to be used commercially.4' the writer describes the general problem area or the current research focus of the fi eld. Notice that the author is still not describing the specifi c problem which this research article will deal with; s/he is describing the current focus of the fi eld, a problem which many researchers in this fi eld are interested in and which leads to the specifi c problem which will be addressed in this article. Remember to keep this general description of the problem area
Introduction — Writing Task 21 or current research focus brief, or you will fi nd that you begin to give a specifi c description of what your research is trying to achieve, and it's still too early in the Introduction for that. As you can see from Sentence 4, you may need a research reference when you describe the problem your paper will deal with; however, if it is a well-known problem (rather than a recent issue, as in Sentence 4), then it is not necessary to provide a reference. In Sentence 5 'One way to toughen polymers is to incorporate a layer of rubber particles.5' the writer provides a transition between the general problem area and the literature review. As a general rule, you should include references to previous or current research wherever it is useful, even in a sentence whose function is primarily to provide a transition. Make sure that the superscript reference number includes all and only the work referred to in the sentence (see the notes on Sentence 6 below for more about this). In Sentence 6 'For example, Penney et al. showed that PLA composites could be prepared using blending techniques6 and more recently, Hillier7 established the toughness of such composites.' the writer provides a brief overview of key research projects in this area. You can't just 'pour' the literature review onto the page in any order; you should arrange your references and studies so that the reader is able to process them in a logical way. Here are three common options: • chronological: Deal with the research in chronological order. Th is may be appropriate, for example, if the development of your fi eld is related to political decisions. • diff erent approaches/theories/models: Group projects or studies according to their approach or methodology. Grouping similar projects together helps you avoid the 'tennis match' eff ect where you