（）的主要目的是减少淬硬倾向，防止产生裂纹。
参考答案：焊前预热
列属于主刑的有[ ]
①管制、死刑
②拘留、罚金
③有期徒刑、拘役
④无期徒刑、剥夺政治权利
A．①②③
B．②③④
C．①③
D．①④
________，they found that he was gradually recovering.
A．To their much delight
B．To much delight
C．To much their delight
D．Much to their delight
