备用表达式
alternate───v.（使）交替，（使）轮流；n.替换物，代理人；adj.交替的，轮流的；间隔的，每隔（……天等）的；（一或多个事物）另外的，可供选择的；（两者）互不相容的；另类的，非传统的；（叶、芽）互生的
expression───n.表现，表示，表达；表情，脸色，态度，腔调，声调；式，符号；词句，语句，措辞，说法
proverbial expression───谚语
alternate segment───交错弓形
alternate angle───交错角，错角；内错角；（交）错角
protein expression───蛋白质表达
alternate key───备用关键字；[计]替换关键字；备用[辅助]关键字
constitutive expression───组成型表达
alternate in───轮流
takes semantics as a main thread to discuss the expression of alternate category in modern Chinese.───以语义为纲，探讨现代汉语交替范畴的表达。
gene expression profile of those cells shows little difference between them and stem cells with alternate fates isolated from the upper airways.───这些细胞聚集形成“豆荚状”并启动肺泡相关基因的表达，而这些具有小的空心结构的肺泡正是肺部进行气体交换的位点。
As in most every language, Scala's if evaluates a conditional expression, then proceeds to a block if the result is true or branches to an alternate block if the result is false. A simple example.───和大多数语言一样，Scala的if测试一个条件表达式，然后根据结果为真或假来跳转到响应语句块中。