It was invented by three scientists.
It was big and heavy.
It was tiny and flat.
It could create electricity.
More and More solar cells are sold.
The price of solar cells decreases every year.
Solar energy does not harm the environment.
Solar energy will never be used up.
Squirrels are storing up nuts for the winter.
He will go to a big department store.
I need to go to the store for some milk.
He hoped the electronic equipment was safely stored away.