______ that the earth was flat？A．Used it to be thoughtB．Did it used to be thoughtC．Was it

___________ the earth to be flat, many feared that

___________ the earth to be flat, many feared

______ the earth to be flat, many feared that Columbus would fall off the edge of the eart

Its said that Dr. Anderson was breaking fresh______in cancer research.A．floorB．landC．earth

Until the 16th century the earth______to be flat.A．is believedB．has been believedC．believe

When I was a child my teacher told me that the earth ______round the sun.A.to goB.goesC.has goneD.g