that的复数形式是those
this的复数形式是these
If you think about it, those children must be at school by now.
想想吧，那些孩子现在一定在学校了。
I think you'll find these more comfortable than those.
我想你会觉得这些比那些更舒适。
All these changes happened over a period of time.
所有这些变化都是在一段时间内发生的。
Teachers are up against some major problems these days.
老师们最近面临着一些重大问题。
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