Question

Поставьте глаголы в past simple or present perfect. 1. In 1998 the famous Explorer _ ( publish) his first book

Answer 1

Рast Simple:
In 1998 the famous Explorer published his first book.
 
Present Perfect:
In 1998 the famous Explorer has published his first book.

Answer 2

Published.
___________

Answer 3

In 1998, the famous Explorer published his first book.