1、四十的英文：forty。

2、参考例句：

Among this money there was one forty-sou piece。里面有一个值四十苏的钱。

Younger/older than forty,fifty,etc years of age。不足[已过]四十、五十岁等.

Mr. Smith is still in his forties.史密斯先生才四十几岁。

a steamer of 40 feet beam。船幅四十呎之轮船。