which of these animals would be good pets?其中would be是虚拟语气么？如果不是是什么啊？

表示不确定。有有可能的意思在里面。

would的几种用法：这里表示可能。

Used after a statement of desire, request, or advice:
用于表愿望、请求或建议的陈述之后：
I wish you would stay.

我希望你能留下来
Used to make a polite request:
用于有礼貌的请求：
Would you go with me?
你愿意和我一起去吗?
Used to indicate uncertainty:
表示不确定之意：
It would seem to be getting warmer.See Usage Note at if
天气似乎变得更暖和了参见