late O.E. þe, nominative masculine form of the demonstrative pronoun and adjective. After c.950, it replaced earlier se (masc.), seo (fem.), þæt (neut.), and probably represents se altered by the þ- form which was used in all the masc. oblique cases (see below). O.E. se is from PIE base *so- "this, that" (cf. Skt. sa, Avestan ha, Gk. ho, he "the," Ir., Gael. so "this"). For the þ- forms, see that. The s- forms were entirely superseded in English by mid-13c., excepting dialectal survival slightly longer in Kent. O.E. used 10 different words for "the" (see table, below), but did not distinguish "the" from "that." That survived for a time as a definite article before vowels (cf. that one or that other). Adv. use in the more the merrier, the sooner the better, etc. is a relic of O.E. þy, originally the instrumentive case of the neuter demonstrative þæt (see that).
masc. Fem. Neut. Plural
Nom. se seo þæt þa
Acc. þone þa þæt þa
Gen. þæs þære þæs þara
Dat. þæm þære þæm þæm
Inst. þy, þon -- þy, þon --
词根记忆：
art.
这(那)个;这(那)些(指特定的人或物)Have you got the letters I sent you?我寄给你的那几封信收到了吗?