有时物质（总称，不可数）发生变化，（这些具体的物质，可数）再也不会恢复到原来的状态。

Sometimes changes take place in matter and the substances never return to their former condition .

youdao

有时物质（总称，不可数）发生变化，（这些具体的物质，可数）再也不会恢复到原来的状态。

Sometimes changes take place in matter and the substances never return to their former condition .

youdao