Выделите конструкции с неличной формой глагола: 1. the impression of bar codes on letters is considered to be of the basic methods of achieving mechanization in the post service. 2. the load is resonant circuit tuned to the frequency of the signal applied to the input of the stage, this resonant circuit being either a single tuned circuit or a band-pass filter. 3. radio frequency amplifiers in which single-tuned circuit serve as a load are known to be tuned amplifier. 4. visual communication allows misunderstandings to be instantly corrected.
