fall ill和be ill的区别：fall ill是瞬间性动词，不可以延续，所以不能和since短语连用。be ill是延续性状态，所以可以跟since短语。两个词语都表示生病的意思，fall ill表示生病的过程，be ill表示生病的状态，不是任何时候都可以互换的。

fall ill造句：

If you don't eat on time and go to bed on time，you will fall ill。如果再不按时吃饭，按时睡觉，你就会病倒的。

She hasn't had a rest for days，and I'm afraid she'll fall ill。她已经好几天没休息了，我担心她会病倒。

The grandmother next door suddenly fell ill and soon passed away。隔壁奶奶突然病倒了，不久就去世了。

be ill造句：

She has been ill since she came home from the rain at the seaside yesterday。自从昨天在海边淋雨之后，回家她就生病了。

She doesn't want to eat anything because she has been ill for a while。因为她这段时间生病了，所以什么东西都不想吃。

Since his illness he has been unable to do anything but lie in bed。自从他生病之后很多事情都做不了了，只能在床上躺着。