4. What is the main idea of this paragraph. Use evidence to support your answer

Today there are cell phones, which do not need wires. They use signals that travel through the air,
carried by systems that depend on the science of physics. Many people now do not have a landline any
more, and just depend on their cell phone. The cell phone is changing communication and even
impacting how people live. It can connect people through texts as well as voice. It can download music
from the Internet. Some people even use their computers to talk to other people with video screens.
Those are the latest innovations 3 in communication. So the telephone is still changing