Several.
6-11
Several Weeks
It depends, some tunnels are several miles long.
Radio waves typically have long wavelengths ranging from several millimeters to several meters. Their long wavelengths enable them to travel long distances and penetrate obstacles such as buildings, making them useful for communication over long distances.
several hours
several days
several days
several generations
several generations
several generations
Anywhere from less than 1 cm to several inches long.