I can't tell which one is her best book as I am not familiar with her books.

我不知道哪一本是她最好的书，因为我不熟悉她的书。

youdao

I am not familiar with his character.

我不了解他的性格。

《新英汉大辞典》

I am an alien, I am not familiar with the city.

我是个外国人，对这个城市不熟悉。

youdao

"I am not familiar with the reasons" that the subpoena was written so broadly, he said.

WSJ: Lawmakers Press Eric Holder on AP, IRS

Though I am not very familiar with the program, one irony here is that the fastest growing category is the 8.7% growth (nearly 13% per pupil) in spending with BOCES, a New York initiative that was supposed to reduce administrative costs in public schools.

FORBES: Government Not Only Too Large, But Spending the Money in All the Wrong Places

Further, I am not nearly as familiar with the Russian economy as I am with the rest of the pack, so I will take a rain check on this.

FORBES: Connect