下列哪些是我国常见的咯血原因()。
A.肺结核
B.支气管扩张
C.慢性支气管炎
D.肺癌
E.风湿性心脏病二尖瓣狭窄
参考答案:A, B, D, E
________ the earth to be flat, many feared that Columbus would fall off the edge of the earth.
A.Having believed
B.Believing
C.Believed
D.To believe
与a相邻的两个整数是( ),( )。