2、来自古英语 thanne,在此之后，然后，来自 Proto-Germanic*thana,那个，来自 PIE*to,指示代词， 词源同 this,that.其与拼写变体形式 than 现已产生词义和用法上的差别。
2、then: [OE] Then was formed from the ancient demonstrative base *ta-, which also underlies English that and there. Its West Germanic relatives include German dann and Dutch dan. It is ultimately the same word as than.=> than, the, there
4、adverb of time, Old English þanne, þænne, þonne, from Proto-Germanic *thana- (cognates: Old Frisian thenne, Old Saxon thanna, Dutch dan, Old High German danne, German dann), from PIE demonstrative pronoun root *to- (see the). As a conjunction,"in that case, therefore,"in Old English. As an adjective,"being at that time,"from 1580s. As a noun from early 14c. For further sense development, see than. Similar evolutions in other Germanic languages; Dutch uses dan in both senses, but German has dann (adv.)"then,"denn (conj.)"than."Now and then"at various times"is attested from 1550s; earlier then and then (c. 1200).