Tham khảo tài liệu 'the grammar of the english verb phrase part 60', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 406 8. Temporal domains and relative tenses theoretical foundations he would wait until his wife arrived I would arrive . If we assume that the meaning of until includes an implicit orientation time until means until the time that the use of the past tense is explained naturally it represents the situation time of John s wife s arrival as T-simultaneous with the implicit orientation time. The concept of relative past tense is also necessary to account for the obligatory use of the preterite in the adverbial time clauses of examples like the following Maud knew that John would leave before Mary arrived I would arrive . As noted in the before-clause in this example is interpreted as not-yet-factual at the binding time more specifically as not-yet-factual at the situation time of the head clause what Maud knew was that Mary would not yet have arrived when John left. The same applies to the until-clause in the following example Maud expected that John would wait until Mary arrived I would arrive but she couldn t know that John would be waiting in vain because Mary wouldn t make it to the meeting-place that day. . The until-clause has a similar not-yet-factual at the head clause-situation time interpretation The obligatory use of the past tense in such time clauses is generally looked upon as puzzling. It seems illogical that unlike many other languages English does not allow the use of the conditional tense which represents a situation time as T-posterior to an orientation time in a past domain to refer to a situation time which must actually be interpreted as W-posterior to an orientation time in a past domain. However these data do not really present a problem if one knows that the temporal conjunctions before until after since and when resemble the phrasal conjunction by the time that in that they are interpreted as before I until I after I since I at the time that see . Diachron-ically the present-day conjunctions before until after and since .
