They send signals back.

Meaning: This means that satellites communicate with us by sending messages.

Choice of Words: They refers to satellites. Send means to transmit or deliver something. Signals are messages or data sent over a distance. Back means to return to the starting point. Together, this sentence shows that satellites transmit messages back to Earth.

Alternative Expressions

The machines communicate with each other.

Meaning: This means that the machines are talking to each other. It's like saying, The computers are communicating with each other to share data.

Choice of Words: The is a determiner that refers to a specific noun. Machines are devices that perform a task. Communicate is a verb that means to share information or ideas. With is a preposition that means together or in the company of. Each is a determiner that means every one of two or more. Other is a determiner that refers to a different person or thing. When you put them together, "The machines communicate with each other" means that the specific machines are sharing information or ideas together.

The robots are controlled by a computer.

Meaning: This means that the computer is telling the robots what to do. It's like saying, The game is controlled by a computer, so it knows what to do next.

Choice of Words: The is a determiner that refers to a specific noun. Robots are machines that can do tasks on their own. Are is a verb that means to exist or to be. Controlled is a verb that means to direct or manage. By is a preposition that means because of or as a result of. A is a determiner that refers to one of a kind. Computer is a machine that can do calculations and store information. When you put them together, "The robots are controlled by a computer" means that the specific robots are directed or managed by one specific computer.

Related Expressions