Yuri Gargarin _________________to space in 1961.
traveled
was traveling
has traveled
Over the last decades, there___________ enormous advances in the field of space exploration.
were
was be
have been
was
The Apollo 11 mission ________________ more than 25 billons dollars.
has cost
was costing
cost
Some people ______________ that the moon landing was faked.
has said
was saying
have said
NASA _______________millions of dollars trying to create a pen that could work in zero gravity.
was spending
spent
has spent