Each cylinder is closed at the top by a （）， made of a special heat-resistant steel.
举一反三
- Each cylinder has one starting valve which is usually opened by air pressure and closed by （）
- High-speed steel is also___________________(know) as self-hardening steel.
- On top of scavenging air box is mounted a strong cast iron frame for each cylinder known as（）
- Steel structure involves sub-structure or members in a building made______ structural steel.
- The top of the cylinder block is covered with the cylinder head. ( )