their

来自 they,他们，-r,所有格后缀，字母 y 音变为 i.

their

their: [12] Like they and them, their was borrowed from Old Norse. Its source was theirra, the genitive plural form of the demonstrative adjective sá. The pronoun form theirs [13] is an English creation.
=> them, they

their (pron.)

plural possessive pronoun, c. 1200, from Old Norse þierra "of them," genitive of plural personal and demonstrative pronoun þeir "they" (see they). Replaced Old English hiera. As an adjective from late 14c. Use with singular objects, scorned by grammarians, is attested from c. 1300, and OED quotes this in Fielding, Goldsmith, Sydney Smith, and Thackeray. Theirs (c. 1300) is a double possessive. Alternative form theirn (1836) is attested in Midlands and southern dialect in U.K. and the Ozarks region of the U.S.

1. They have maintained their optimism in the face of desolating subjugation.

面对遭征服的悲惨命运，他们保持了乐观的态度。

2. He said they should turn their fire on the Conservative Party instead.

他说他们应该掉转枪口，向保守党开火。

3. Husband and wife are now taxed separately on their incomes.

现在夫妻双方分别按各自的收入纳税。

4. They had a snobbish dislike for their intellectual and social inferiors.

他们非常势利，不喜欢智力和社会地位不如自己的人。

5. Their first car rolls off the production line on December 16.

他们的第一辆车于12月16日下线。