Scientists think that there has been life for__31_ of years. However we haven’t found life on other planets _32_ . The earth is a planet and it _33__ around the sun. Seven other planets also go _34_ the sun. The sun and its planets are __35 the solar system. The solar system is a small part of our galaxy.
Scientists __36_ lots of spacecraft to look at other planets in the solar system, and some spacecraft have gone __37_ the solar system. However, no one __38_ any life in space yet.
But why has no one from other planets sent us a message ? Have they tried to send _39_ to us ? _40_so many stars in the universe, are we alone, or is there life out there in space ? We don’t know.
A.thousands B.millions C.hundreds D.billion
A.already B.never C.yet D.just
A.go B.turn C.travel D.goes
A.to B.back C.around D.into
A.called B.call C.calling D.calls
A.send B.sent C.have sent D.will send
A.out B.beyond C.into D.up
A.discovered B.discovers C.has discovered D.have discovered
A.message B.informations C.information D.news
A.With B.Have C.Use D.Because