He was a great and valued personal friend whom I've known for many years.

他是个非常好的、很宝贵的私人朋友，我们已相识多年。

《柯林斯英汉双解大词典》

In fact, fossil beds containing soft-bodied animals have been known for many years.

事实上，含有软体动物的化石层已经被发现很多年了。

youdao

The benefits of a high folate diet have been known for many years.

受益于一个高叶酸的饮食已经知道了很多年。

youdao

A building that houses the Embassy of Indonesia, for example, was known for many years as the Walsh mansion.

VOA: special.2009.09.21

We have known for many years that autism is more common in boys than girls.

CNN: How girls and boys differ when it comes to autism

In 1997, when he was 95, he proposed to Monique Huiskamp, whom he had known for many years.

ECONOMIST: Hartley Shawcross

Matt Blaze is a senior researcher at the University of Pennsylvania and whom I have known for many years.

FORBES: Free Speech v. Denial Of Communications For Public Safety Agencies?