【简答题】人类发展的历史进程中人们不断研制出各种不同的用具,制造用具的材料也在不断地发生变化,金属制品因其美观、耐用、轻便易成型而被人们广泛利用,请根据所学知识及生活知识参与有关金属及其制品的讨论. (1)以下工具的制作过程中没有发生化学变化的是______. A. 原始人制作石刀 B.冶炼青铜 C. 炼铁 (2)请将以下金属材料的冶炼按年代的先后顺序排序______(填序号). A.铁 ...
【单选题】夯机作业四周2米范围内不得有非操作人员。多台夯机同时作业时,其并列间距不宜小于5米,纵列间距不宜小于( )米。
【单选题】_______ there are many different types of food, some animals spend their lives eating only one type.
【简答题】In some Western countries, there are many opportunities for s who want to improve their lives. There are public schools you can attend. In the schools, you can take things like English, arithmeti...
【单选题】如图所示,已知直线AB的两面投影,则AB为
【判断题】我国支付结算实行统一领导,分层管理的模式
【简答题】There are many different ________(type) of languages in the world .
【单选题】_____there are many different types of food, some animals spend their lives eating only one type.
【单选题】如图所示,已知直线AB的两面投影,则AB为
【单选题】如图所示,已知直线AB的两面投影,则AB为