Iron and steel expands when heated and ______ when cooled.A．shrinksB．contractsC．condensesD

The burning of the fuel adds more heat to the air charge, causing it to expand and force t

Which of the listed effects represents the purpose of heat treating steel？A.Develop ductil

Each cylinder is closed at the top by a _____, made of a special heat－resistant steel.A.cy

The iron and steel industry ______ an important part in our national economy.A．playsB．play

Whats the main industry of Bedford？A．Coal.B．Iron and steel.C．Car.D．Education.

It is time we（)computers to the production of iron and steel. A. will apply B. appl