Some festivals are held to honor the dead or to satisfy the ancestors, _____might return either to help or _______.

A．who; to do harm

B．which; do harm

C．that; to do harm

D．who; doing a harm

影响焙烧最高温度的设定因素？环式焙烧炉、车底式炉及隧道窑最高温度如何设定？