【正文】 initial position。 and (c) that medial positions are rare for most connectors, and final positions even rarer. 7) The only attempt known to us to explain differences in position on semantic grounds is an unpublished paper by Salera (1976) discussed in CelceMurcia and LarsenFreeman (1983). 8) In the present paper, we report on a preliminary study of sentence connector position in a sample of twelve published articles.9) Frequency studies of their occurrence in academic English extend at least as far back as Huddleston (1971). 10) The Salera paper deals only with adversatives like however and suggests that initial position reflects something contrary to expectation, while medial position reflects a contrast that is not necessarily unexpected. Part III. Tenses in the IntroductionStage 1: Current KnowledgeUse the present tense when stating or reporting established facts:Fine motor skills require integrating muscular, skeletal, and neurological functions.When reporting findings from multiple previous studies, use the present perfect tense:Previous studies have indicated the need to further examine X.Stage 2: Literature Review1) Use the present tense when reporting established facts:The salt in most oceans is approximately 97% sodium chloride (Ritchie, 199).2) when referring to a single, previous study, use the past tense:Kurtz (2008) found that instructors allocated equal time to each group.Note that the above sentence has two verbs. The first verb, found, describes what Kurtz did in this 2008 study. The second verb, “alloated,” is in the past tense because it describes what the instructors in this study did at the time the research was conducted. If this verb (called a verb plement were written in the present tense, the statement would be expressing a fact that is true for all instructors everywhere. Consider the next sentence and note the tense of the second verb:Baggio and Klinsmann (1994) revealed that DNA polymerase performs a vital function in DNA replication in animal cells.In this example, the first verb is written in the past tense, again to explain what this study did. However, the verb plement (the second verb in the sentence) is written in the present tense because the finding of this study was established as a fact and, therefore, true for everyone everywhere.3) Use the present perfect tense when reporting findings from multiple previous studies:Several researchers have studied the relationship between classroom lighting and standardized test performance (Jens, 2006。6Kiby et al, 2008。 Miner, 2009).Note how the different verb tenses used in the following three sentences slightly change the meanings: Owen and Shearer (2002) discovered that memory load affects brain activity.Owen and Shearer (2002) discovered that memory load affected brain activity. Owen and Shearer (2002) suggested that memory load may affect brain activity.The first sentence uses the present tense affects to claim this study39。s finding as a fact. The second sentence uses the past tense to report the finding as being limited to the circumstances of the involved study, and the third sentence uses both a tentative verb “suggested” and a modal verb “may” to describe the implications of the finding.Stage 3: Knowledge Gap1) Report facts and currently accepted methods using the present tense:Little information is available on the risks and benefits of X vs. Y.2) Refer to multiple previous studies using the present perfect tense.However, few studies have reported the effects of antioxidant seeds on the endocrine system.Stage 4: Problem Statement1) Use the present tense when writing reportfocused statements:The aim of this paper is to determine the principal mechanical parameters of thin film deposited on a circular glass substrate.2) When writing researchfocused statements (referring to your own study), use the past tense:The purpose of this study was to determine whether or not a genetic correlation exists between performance levels at high and low temperatures.Stage 5: Rationale for Study (optional)When expressing expected outes or offering future remendations, use the present tense with conditional modal verbs(such as could, may, and might):This research may provide an alternative to the mon field measurement of soil erosion and runoff.