15远中邻合面窝洞，按Black窝洞分类法，应是:（）
A．Ⅰ类洞
B．Ⅱ类洞
C．Ⅴ类洞
D．Ⅳ类洞
参考答案：B
The students were all tired, but ___ of them stopped to have a rest．
A．none
B．each
C．either
D．neither
论述我国《合同法》对要约生效的规定。
