undersea mountains generally form when volcanic mountains rise up_英语解答

undersea mountains generally form when volcanic mountains rise up from the seafloor but fail to reach the surface,while (those that) break the surface become islands.
这里that有什么意义?
定语从句that which一般情况可以省略吗?什么时候不能省略?

人气：247 ℃　时间：2020-05-18 18:18:33

解答

undersea mountains（主语） generally form（谓语） when volcanic mountains rise up from the seafloor but fail to reach the surface时间状语while (those《those 指代volcanic mountains 》 that break the su...