There is no standard measure. The monitor that I am using now is 71 cm long. Also, like TV screens, the size of a monitor is the length of its diagonal.
4inches
There are many online shops that sell computer monitor. Amazon.com is one of online shop that sells computer monitor with any kind of models and specifications. You can visit www.amazon.com
Earthworms vary greatly in their length.
1 meter
About 4 millimeters
300 feet
12mm
CNET provides a guide on how to best monitor computer activity, especially if you want to check up on your child's computer activity. You can also use the history tab on the computer.
Monitors serve to display what is inputted on a computer. There are various types of monitors, but you should choose the one that is best for your vision.
21 feet
2 centimeters
about 3 meters