铸铁冷焊的特点?
参考答案:
(1)工艺简单,成本低,效率高,劳动条件好;
(2)不必预热;
(3)焊接不受焊缝空间位置的限制;
(4)接头组织不均匀,白口较多,加工困难。
____You hurt her ,Mike.
_____Yes, but I didn’t _________.
A.mean to do
B.mean to
C.mean not to
D.mean to it
化学药品注册分类中,已在国外上市销售但尚未在国内上市销售的药品包括哪几类?