An elephant a trunk.[ ]
A. has
B. to have
C. have
答案:A
Austin-Flint杂音见于()
A.主动脉瓣关闭不全
B.二尖瓣关闭不全
C.三尖瓣关闭不全
D.动脉导管未闭
E.室间隔缺损
拱桥按拱圈的横截面型式分为()
A、板拱桥
B、肋拱桥
C、双曲拱桥
D、箱形拱桥