已知图G有11条边，由1个4度顶点，4个3度顶点，其余顶点的度数均小于等于2，则G中至少有( )个顶点。
A．7
B．8
C．9
D．10
参考答案：B
. ---Learning a language isn’t easy. It takes time.
---I agree. ________. There is no short cut.
A．All roads lead to Rome
B．Rome was not built in a day
C．Practice makes perfect
D．Slow but sure wins the race
所有金属都可以用氧气—乙炔气进行切割。
