Посмотрите правильно я выбрала в тексте предложения, в которых глаголы-сказуемые употребляются в пассивном состоянии.

Television provides a means of viewing the images of objects that are out of sight, i.e. far removed from the observer.
The images of moving or stationary objects are converted into electric signals and these signals are transmitted by a television transmitter. The television receiver (TV-set) picks up these signals and performs the reverse conversion of electrical signals into the image displayed on the screen of a cathode ray tube (CRT). Television signals can be transmitted by means of transmission lines as well as by radio.
The transmission of video signals is more complicated than the transmission of audio signals by means of radiowaves. There is a difference between the perception of audio signals and video signals by the human being. No matter how complex the audio signal is, the human ear interprets it as the sum total of all its components, i.e. as a signal sound. The human eye, on the other hand, can perceive many different objects at one and the same time. Modern television techniques have taken all the peculiarities of human sight into consideration.
The iconoscope camera tube was developed as far back as the early thirties. Later, other types of camera tubes came into use, such as the super-iconoscope which is commonly known as the image iconoscope. The tube in the television receiver, that provides picture display, is called the picture tube of kinescope.
The image of an object is projected onto the camera tube. The electron beam of this tube scans the image point by point. The beam scanning is controlled by a scan unit. At the tube output, pulses corresponding to the image are generated. These signals are usually termed the picture signals.
These pulses are amplified and used to drive the television transmitter, where they modulate the transmitter carrier. Transmission is usually achieved by amplitude-modulation techniques.

1. Television provides a means of viewing the images of objects that are out of sight, i.e. far removed from the observer.
2. Television signals can be transmitted by means of transmission lines as well as by radio.
3. The human eye, on the other hand, can perceive many different objects at one and the same time.
4. These signals are usually termed the picture signals.

Пользовалась опредилением :

Предложения с глаголом-сказуемым в форме пассивного состояния употребляются в английском языке, когда главный интерес для собеседников составляет лицо или предмет, на которые направлено действие (объект действия) , а не тот, кто выполняет действие (субъект действия) , как в предложениях с глаголом в форме активного состояния.