反射回声的强度取决于:①界面两边声阻抗差;②声速的衰减程度;③入射声束与界面的角度;④声束传播距离()
A.①②③
B.①③
C.②④
D.④
E.①②③④
参考答案:E
His timely warning was_____ help us avoid being cheated.
A.so as to
B.such as to
C.so that
D.such that
简述全能普化型行政功能文化和有限分工型行政劲能文化的内涵。