[问答题,简答题] 避免引起铸件砂眼的具体措施有哪些?

IgG分子与C1q的结合位点是() ["A．vH","B．CH1","C．CH2","D．CH3","E．CH4"] 免疫接种后首先产生的抗体是() ["A．IgG","B．IgA","C．IgM","D．IgD","E．IgE"] 人类在胚胎期合成的Ig是() ["A．IgG","B．IgA","C．IgM","D．IgD","E．IgE"] 避免产生缩孔的措施有哪些? 铸件表面的缩孔是怎样形成的? 避免引起铸件砂眼的具体措施有哪些?