but后面的句子省略主语的使用方法

The old woman had no tap where she lived, but had to bring in the water from a pump.

这个 but 后面的句子没主语，还是转折连词表示“但”的意思吗？

The old woman had no tap where she lived, but had to bring in the water from a pump.

【翻译】这位老太太住的地方没水龙头，她只能从水泵里取水。

【剖析】连词but 的前一分句含有否定词no，nothing 等时，不肯定都翻译成“但”，可以翻译成“只有；只能”。had to bring...之前，省略了she。