以长为13cm、10cm、5cm、7cm的四条线段中的三条线段为边，可以画出三角形的个数是 _________
3
Let ______________ help you.[ ]
A. I
B. my
C. me
Very long，complex expressions in program are difficult to write correctly and difficult to __( )__.
A．defend
B．detect
C．default
D．debug
