Question

关于since引导时间状语从句时的用法

Answer 1

since 在作连词使用时,有两个主要词义：从过去的某一个时间点至说话时为止,中文译作“自从”、“从.起”等.其时态特点是主句为完成时,从句为过去时.这是由于这个“过去的某一个时间点”所决定的 .你们老师对有延续含义动词的解释是对的.表示原因、起因等语义,中文译作“由于”、“因为”、“鉴于”等.since 的这一种词义使得其谓语时态与主句时态相一致,可以是现在时、过去时、将来时和完成时；而主句并无一定要用完成时的要求. 你所给的例句中,I’ve written her 20 letters since I have been here 和 I’ve written her 20 letters since I was here 中 since 的词义并不一样,前句是上面谈的第二个解释,后句为第一种解释. That's changed since I was here（That has changed since I was here）是个歧义句：That has changed since I was here（last time）. 自从我上次来这里,那个已经有变化了.That has changed since I was here and I didn't see that. 有了变化了.我上次来时并没有见到那个.要表达“我到这里之后一切就变了”,这句话会说成 That's changed since I came here,否则逻辑上说不过去.