您好，在含有比较级的句子中，that作为比较对象，代指单数或不可数名词，而those代指可数名词复数。例句：
The weather in Beijing is colder than that in Guangzhou.
北京的天气比广州要冷一些。
分析：that代指the weather。
The students in our class are much taller than those in your class.
我班的同学要比你们班的同学个子高很多哦。
分析：those代指 the students.