She fell ill with measles.

她患了麻疹

If I fall ill, I'll see my doctor.

如果生病了，我会去看大夫。

What will happen when she fall ill?

如果她生病了，又会发生什么？

Jack looks as if he is going to fall ill.

杰克看上去好像要生病的样子。

What if I fall ill while I'm away on holiday?

如果我在放假时生病了怎么办？

It is easy for the old to fall ill in winter.

老年人很容易在冬天生病。