It is much colder in Beijing than Shanghai.修改错误The ill boy was late for school yesterday.修改错误（两题都要说明理由）

It is much colder in Beijing than Shanghai.修改错误The ill boy was late for school yesterday.修改错误（两题都要说明理由）
It is much colder in Beijing than Shanghai.修改错误
The ill boy was late for school yesterday.修改错误（两题都要说明理由）

It is much colder in Beijing than Shanghai.修改错误The ill boy was late for school yesterday.修改错误（两题都要说明理由）
It is much colder in Beijing than in Shanghai.比较不一致
The sick boy was late for school yesterday.ill只能做表语,不能做定语

much改成more，从colder得知这里要用比较级，much的比较级是more，与than构成固定搭配more than.
ill改成sick（ill只能做表语，表语是用在be动词和系动词后的，不可以用在名词前面，而sick既可以作表语也可以作定语）
不明白可以问我。

It's much colder in Beijing than (it is ) in Shanghai.
The sick boy was late for....
Sb is ill or sick.
But we can't say, an ill boy. Instead, we must say, a sick boy.
That is, an ill boy doesn't mean a sick boy.
Is ' an ill boy" an expression? Sure. it is. But it means " a bad or ill- willed boy".