（）通常指自然、政策、市场的不确定性。
参考答案：外生不确定性
No one will be sure ____________ in a million years.
A．What will man look like
B．man will look like what
C．what man will look like
D．what look will man like
胃溃疡的典型X线征象是（）。
A.黏膜中断破坏
B.龛影
C.充盈缺损
D.排空慢
E.胃腔增大
