《技规》对单机挂车辆数有何规定？
参考答案：
单机挂车的辆数，线路坡度不超过12‰的区段，以10辆为限；超过12‰的区段，由铁路局规定。
26. According to the arrangement, the newly-elected president _______a speech to his supporters from 8 to 10 o’clock tomorrow morning .
A．is giving
B．will be giving
C．gives
D．will have given
"龙生龙，凤生凤，老鼠的儿子会打洞"这句谚语说明的生物现象是
