A useful echo is echolocation, which is used by marine animals such as dolphins to locate and then hunt their prey
Some yes,some,no. There are uesful and not-so-useful in both sexes. It really depends on your definition of "useful".
Because they are useful.
Computers are so useful to us.Bert is not a very useful person.I find that the phone is a useful invention.Make yourself useful and pass me the spanner.Hopefully these sentences are useful to you.
Yes so they have some obediance
Well about 500 million people world wide speak it or some derivative of it so its pretty useful
Electromagnets are useful because some machines need magnets that can stop being magnetic. In junkyards, some machines need to pick up metallic objects, so they need magnets that can turn on and off, which is where a electromagnet becomes useful.
dimensional anaylisis is useful for many reasons, mainly because without it YOU AINT SHIzznitt so there for it is very useful
they're useful so people can get around and people r lazy
Fuel is so useful to spacecrafts because without the fuel the spacecraft would not go.
Because it looked fun and useful, so they brought some.
It is useful for you to know how to talk so that you can communicate with other people.
They are useful because they keep your joints working and enables you to move so that's why they're useful :) You're Welcome -Alyssa :P