Twist drill are made of

Leather and Worn

Leather and Worn type of apron is used during welding.

Using gloves

Overlap position

In Lap joint, plates are kept overlap position.

None of these

When steel has been fully deoxidized before casting and no gas was evolved during solidification, the resultant steel is known as killed steel. It is combined with an agent like casting before use. This steel is called "killed" because it quietly solidifies in the mold and no gas evolves.