Following are examples of three metamorphic rocks and a list of their uses. Marble is a metamorphic rock that is used to make floor tiles, counter tops and it is carved into statues and was used extensively in the building of the Roman Colosseum and other historic buildings. Slate is another metamâ¦.
A hex key, Allen key or Allen wrench is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head (internal-wrenching hexagon drive).
Primary Key. A Primary key uniquely identifies each record in a table and must never be the same for the 2 records. Primary key is a set of one or more fields ( columns) of a table that uniquely identify a record in database table. A table can have only one primary key and one candidate key can select as a primary key.