forty

四十

Twenty plus twenty equals forty.

二十加二十等於四十。

四十幾歲、四十多歲常用複數 forties

She started learning the piano in her forties.

她四十幾歲才開始學鋼琴。

四十年代常用複數 the forties

The photograph was taken in the forties.

這張照片是在四十年代拍的。

四十的、四十個

Forty students signed up for the summer course.

有四十名學生報名參加暑期課程。