——Are you and your parents going to visit friends in Shandong?——Yes, and while we ____ with them, we're going to spend a few days in Qingdao.
A:stayed
B:have stayed
C:were staying
D:are staying
给物质加热时,应用酒精灯灯焰的____部分,因为这部分温度____;用托盘天平称量时,应把砝码放在____盘;加砝码时,应先加质量____的砝码,砝码要用____夹取;给试管里的液体加热时,试管里的液体体积一般不要超过试管容积的____;在实验室里如不小心碰倒酒精灯,洒出的酒精在实验台上燃烧起来,应立即用____扑盖.