1的单数形式，illness

illness就是单数形式。

n. 病疾病The illness is usually terminal.

这种病通常为不治之症。

She is still weak after her illness.

她病后仍然虚弱。

The illness was diagnosed as cancer.

此病诊断为癌症。

Illness had taken a heavy toll on her.

疾病对她的身体造成极大的损害。

Illness had put a brake on his progress.

疾病中止了他的进展。