for a spider always has eight legs and insect never more than six.
insect前面既没有冠词,后面也没有加s,是不可以做主语的
那是不是与spider前的a是共用的?
这句子贼熟……托福题或者哪本语法书上的……
是省略的情况,and前后连接两个句式和语法结构完全并置的语句时相同部分可省略
你分析一下,and后面能省的部分全部都省掉了,包括定冠词,谓语,宾语
写完整：
a spider always has eight legs and an insect never has more than six legs
a和an虽然拼写不同,但是都是冠词,表意也一样,故此省略,并不是共用什么的.
关于所谓的“总称”,给一个对比（牛津）
insect
noun
any small creature with six legs and a body divided into three parts.Insects usually also have wings.ANTS,bees and flies are all insects:insect pests / larvae / species ◆ insect repellent (= a chemical that keeps insects away) ◆ an insect bite ◆ The pesticide is lethal to all insect life.
stationery
noun [U]
materials for writing and for using in an office,for example paper,pens and envelopes
special paper for writing letters on
首先总称会在义项内标出[U],其次释义里面,insect用的是any开头,而stationery上来用的就是复数的materials,所以不存在当总称这一说法,要泛指请加冠词
