请帮忙翻译一下、英文、如果说中国是一棵大树、那么西安便是这棵树的根、

if China were a tree,then xi'an is its root.
要用虚拟语气，因为中国不是树

如果说中国是一棵大树、那么西安便是这棵树的根.

If China can be regarded as a big tree, Xi'an is the root of it.

Xi'an is the root if China is described as a big tree.

If China is a big tree,that Xi'an is a root