since怎么样分辨quot;时间quot;还是quot;缘由quot;

Since mother was ill in the hospital I had to care of her.

句子非常简单,但since根据自从来理解,还是由于来理解呢?

Since mother was ill in the hospital I had to care for her.

连词since 表示“从...以来到今天” 意义时，主句谓语动词用目前完成时。网友的句子，是与从句相同的一般过去时。

所以，since 表示缘由。此句只有依据时态判断since 的意思。

假如主句是完成时 have had，那样since 表示“时间”：

Since mother was ill in the hospital I have had to care for her.

自从母亲生病住院以来，我不能不照顾她。

又如：

Since his illness, he has had to stay out of tennis.

自从生病以来，他不能不一直离得远远的网球了。