He is said to be ill 是一个被动语态，它如何变为主动语态呢？

参考译文：据说他生病了。

回答如下：

People say that he is ill.

上面意思还可以用下面的结构表达。

It is said that he is ill.

备注可以当作一下种句型来记忆掌握并加以熟练应用

(1)It is/was said that sb do sth 有人说/据说

It is said that wisdom is born with a man.
有人说智慧是与生俱来的。

It is said that Guanyuan is  a legendary place.
有人说，四川广元是一块充满传奇的地方。

It is said that God is almighty.
据说上帝是万能的。

(2)sb/sth is /was said to do sth/to be 某人/某物据说做了某事

The jewels were said to be beyond price.
据说那些珠宝价值连城。

These medical herbs are said to act on the heart.

据说这些药草对心脏起作用。

Some of our research may well be said to have reached advanced levels.
我们有些研究工作确实可说已达到先进水平。

Only those can be said to possess transferability.
只有那些才可称其具有可转换性。

A slave may be said to exist but hardly to live .
可以说一个奴隶生存，但很难说他是在生活。

It cannot be said to be good or bad.
这种事无所谓好坏。

A slave may be said to exist but hardly to live.
可以说一个奴隶生存,但很难说他是在生活。

(3)sb(A) say that sb(B) do sth 某人说....

People say that Guanyuan is  a legendary place.
人们 说四川广元是一块充满传奇的地方。