there单数形式是什么

How long have you been living in this country?
你在这个国家居住多久啦？
Well, make up your mind. Which do you want? This one or that one?
哎，拿定主意。你要哪一个？这个还是那个？
I think you'll find these more comfortable than those.
我想你会觉得这些比那些更舒适。