Question

1) The first national park (to establish) in 1872 in the USA.
2) The participants of the conference (just to finish)
the discussion of further ways of the space exploration. 3) An article about the consequences
of nuclear pollution (to publish) in a local newspaper some days ago.
4) An open-air Nature Museum (to visit) by hundreds of tourists every
week. 5) In a year the holidaymakers from different countries (to have)
an opportunity to plan their rest all over the world with the help of the Internet.
6) Frank (to wander) around the old city when he suddenly
(to see) the stranger whose suitcase he
(to take) in the morning by mistake срочно прошу )) 

Answer 1

1) was established
2) had just finished
3) published
4) is visited
5) have
6) was wandering, saw, had taken