2008 年 2 月 7日

When something, then something else 時 。。。

時 (とき) connects two sentences and expresses the time when the state or action described in the main sentence exists or occurs. As shown below, the forms of verbs, い adjectives, な adjectives and nouns connected to とき are the same as the forms when modifying nouns.
Note that the tense of adjective sentences and noun sentences which modify 時 is not affected by the tense of the main sentence.
When the dictionary form of the predicate is put before 時, it indicates the non-completion of the action, and when the た form of the predicate is put before 時, it indicates the completion of the action.
In the first sentence, かえるindicates that at the time being referred to, the action had not yet been completed, that the speaker had not reached his/her country yet, and that he/she bought a bag somewhere on his/her way there. In the second sentence, かえった indicates that the action was completed and the speaker bought a bag after arriving in his/her country.