在英文里,表达两个句子之间因果或转折的关系时,除了用诸如“so”, “yet”, 这样的连词连接两个简单句而构成一个并列句(或包含由because, since, as等连词引导的原因状语从句的复合句,下文会提及),往往还可以使用有因果或转折含义的副词进行断句,把一个中文句断成两句英文句。举个例子,前文中提到的这么一句“钛及钛合金自被引入医疗领域以来,因其良好的生物相容性而得到广泛应用,但由于其耐磨性不高,钛合金不作为承载界面。”用英语表达时,一般会断成两句话:“Since titanium and titanium alloys were introduced into the medical field, these materials have been widely applied due to their good biocompatibility. However, titanium alloys do not have high wear resistance, and hence cannot serve as load-bearing interface.” 在这里,副词however做为第二句话的起头,点明了前后两句之间的逻辑关系。同时,一个长句也被断成了两个短句。
在科技写作中,名词性从句应用比较多的有宾语从句和同位语从句(即从句在主句中分别充当表语和同位语)。举例说明:We hypothesize that XXX can improve the efficacy of XXX treatment. (宾语从句). The fact that titanium alloys do not have high wear resistance makes it impossible to use these materials as load-bearing interface. (同位语从句)。
形容词性从句也就是定语从句,这可能是科技论文写作中应用最广泛的从句类型之一了。我们知道论文中对一个名词或者名词短语的修饰往往比较多而且复杂,这就需要使用定语从句。比如: Recently, XX et al. have identified XXX cells, which possess the ability to proliferate and differentiate into both XX and XX cells. 这里说一下,定语从句的引导词在科技写作中用的最多的是which和that。怎样区别使用这两个引导词呢?在一般的科技写作里,不妨试着遵从如下简单规则:如果引导词前面用了逗号,即上个例句,引导词可用which; 如果引导词前面没有逗号, 引导词用that。比如, XX et al. have identified XXX cells that possess the ability to proliferate and differentiate into both XX and XX cells.
副词性从句在主句中充当状语的角色。在科技论文中,使用最多的包括时间状语从句和原因状语从句。前者多用于描述实验方法,往往由before, after, when等引导词引导,比如: After XXX was removed on day 3, XX cells were further treated with XXXX at a dose of XXX. 原因状语从句由because, since, as, given that等词语引导,如前面所提及,包含原因状语从句的复合句在科技论文里出现的频率还是蛮高的,比如:Because XX do not express XXX genes, these cells are XXXX lineage-specific.
在结束关于复合句的简介之前再说一点,有些时候从句完全可以用短语来代替。比如上段中的第一个例子,可以改写为 “After XXX removal on day 3, XX cells were further …”. 描述简单的原因时,也可以不用原因状语从句而用“because of”, “due to”等引导的短语来完成。
In sophisticated style, you never use "however" to start a sentence, like "However, titanium alloys do not have high wear resistance, and hence cannot serve as load-bearing interface.”