请问老师：

1. that是否只能引导限制性定语从句？

2. 当that引导的定语从句前面有逗号，除了同位语之外，还有哪几种情况呢？

3. It is the greatest building, a truly delightful place,  that looks the same as it must have done 100 years ago with its winding streets and pretty cottages.

这一句的that改成which，句意会发生什么变化呢？

4. This is the Mount Woody, a volcano respected by some locals as the bridge, that connects the island to the gods.

that引导的定语从句是修饰前面的Mount Woody还是bridge呢？按照语法上，that应该修饰Mount Woody。可是从句子意思上来说，应该是“连接小岛和天神们的桥梁”才对。

感谢老师回答。