The period during (when) people (learned to) smelt iron is (called) (the) Iron Age.
A: when
B: learned to
C: called
D: the
A: when
B: learned to
C: called
D: the
举一反三
- 中国大学MOOC: when a bar of iron attracts other pieces of iron，it ____a magnet，and thus the attraction is called mangnetism.
- when a bar of iron attracts other pieces of iron，it ____a magnet，and thus the attraction is called mangnetism. A: will be acted as B: acts as C: is acted as D: has been acted as
- At the top of the A-frames there is a strong cast iron frame called （）.
- When should lessons learned be organized ？（） A: During the project life cycle and at the en B: At the end of the project during closin C: After the end of the project at a project post-mortem meetin D: Lessons learned can be organized when there is time availabl
- （） of the A-frames there is a strong cast iron frame called the scavenging air box.