如果等腰三角形的两边分别是5cm,7cm,则第三边是( )
5或7
What is the calling and distress frequency on a single side band (SSB) marine radiotelephone?()
A.1492 kHz
B.1892 kHz
C.2082 kHz
D.2182 kHz
为什么盾构进出洞要进行端头加固?