Teacher:Welcome to my class.Today we’ll continue the topic of writing scientific paper.

There are two tenses were commonly used in scientific writing: present tense and past tense.In general，the present tense is used for describe established knowledge(including your own published findings)and the past tense is used for theResultsthat you are reporting.Now，I’ll explain how to use them in details:

In the abstract section you’d better describe your investigations in the past tense，introduceMethodsand mainResultsin present tense.In the introduction section we summarise established knowledge so we use the present tense.TheMethodsandResultssection describe what you did and found throughout the study.It’s proper to use past tense.In the discussion section where you compare established knowledge with your own findings，you need alternate between present and past tense.Sometimes even do that in a same sentence.

The last but not the least is do not use words like“maybe”more than once in a sentence.That can drain all forces from the sentence and make it failed in persuasiveness.For example，the sentence“The result of this exploration may indicates a possible discovery of a probably new continent”should be replaced by“Explorers think they discovered a new continent”.In addition，the combination of and/or has no place in scientific writing.That kind of expression disrupts the textual flow.Readers will understand easier through the sentence“The effect of intravenous streptokinase，oral aspirin or both…”but not“The effect of intravenous streptokinase and/or oral aspirin…”

Well，all above are my personal viewpoint.Hope it can help!Goodbye!

老師:大家好!今天我們接著討論撰寫科學(xué)論文的話題。

在寫科學(xué)論文時我們主要用到兩種時態(tài):現(xiàn)在時和過去時。通常表述已有知識(包括自己已發(fā)表的結(jié)果)用現(xiàn)在時;表述文章中報道的結(jié)果用過去時。下面我詳細(xì)的說說這兩種時態(tài)的用法:

論文的摘要部分表述自己的研究工作用過去時。概述試驗方法和主要結(jié)果用現(xiàn)在時。前言部分綜述前人的研究結(jié)果，用現(xiàn)在時。方法和結(jié)果部分表述整個研究的過程和結(jié)果，用過去時。討論部分會把你的研究結(jié)果和已有的事實做比較，需要交替使用現(xiàn)在時和過去時，有時在一個句子中也可以這樣做。

最后還有很重要的一點是，不要在句子中使用兩個以上表示“可能性”的詞匯，那樣會削弱句子的力量，使它缺乏說服力。例如下面這個句子:這次探險的結(jié)果可能表明也許有發(fā)現(xiàn)一個新大陸的可能。就該寫成:“探險家們認(rèn)為，他們發(fā)現(xiàn)了一個新大陸”。此外像“and/or”這樣的組合詞也不要用在科學(xué)論文中。它會妨礙信息的流暢表達(dá)。比如，讀者會覺得“靜脈注射鏈激酶，口服阿司匹林或者兩者共用的效果”比“靜脈注射鏈激酶和/或口服阿司匹林的效果”更好理解。

以上是我的一點個人經(jīng)驗，希望能對大家有所幫助。再見! (續(xù)完)

［注釋］

present tense:現(xiàn)在時態(tài);past tense:過去時態(tài);abstract section:摘要部分;introduction section:前言部分;discussion section:討論部分;MethodsandResultssection:方法和結(jié)論部分;alternate:交替，輪換;the last but not the least:最后但同樣重要的