答案:D
Many early Europeans, ________ the earth to be flat, feared that Columbus would fall off the edge of the earth.
A.believing
B.having believed
C.believed
D.to believe
AIDS的传播途径主要是()
A.呼吸道传播
B.性传播
C.消化道传播
D.接触传播
E.虫媒传播