A phonograph is a machine. It records sound.
A phonograph is a machine that records sound.
A lab is place. We do experiments in a lab.
A lab is a place where we do experiments.
Marconi was a scientist. He invented the radio.
Marconi was a scientist who invented the radio.
Electricity is a type of energy. We use every day.
Electricity is a type of energy that/which we use every day.
Alfred Nobel was a man. His name is now famous.
Alfred Nobel was a man whose name is now famous.
Summer is a season. We go to the beach.
Summer is a season when we go to the beach.
