Riddle, a child, is thin and long, and has a strong ability to measure things. Comparison and measurement,

Answer: a ruler. Note: Ruler is a tool for drawing line segments (especially straight line segments) and measuring length. There are usually scales on the ruler to measure the length.

Rulers are usually made of plastic, iron, stainless steel and plexiglass. Some rulers have holes with special shapes, such as letters or circles, which are convenient for users to draw. They are usually used to measure and calculate the length, and are generally divided into tape measure, vernier caliper, ruler and ruler.

One legend is that ...

One of Lu Ban's inventions is that he can correctly draw a right triangle, also called a class ruler, and can tell craftsmen which sizes are irregular and which ones are unlucky according to the rules of divination (geomantic omen). These rulers can be bought today.

Silk cloth ruler, also known as tailor ruler or cutting ruler, originated from the ruler with class ruler, but it has not been passed down from generation to generation, and has long lost its standard and become another ruler system.