Final answer:
To convert 'Future big cities will block cars' into passive voice, the sentence should be 'Cars will be blocked by big cities in the future'. The passive voice emphasizes the action on the subject rather than the doer.
Step-by-step explanation:
To change the active voice sentence 'Future big cities will block cars' into the passive voice, we should ensure that the subject receives the action. The passive voice structure typically includes a form of the verb 'to be' and the past participle of the main verb, and the doer of the action can be omitted or introduced by the word 'by'. Therefore, the sentence in passive voice becomes: 'Cars will be blocked by big cities in the future'. This makes the sentence focus more on the action happening to the subject (cars) rather than who is doing the action (big cities).
Passive voice constructions are often used to shift the focus of the sentence from the doer to the receiver of the action. Although passive voice sentences are necessary and clear, a paper full of passive voice constructions lacks vitality and becomes wordy. This is particularly important in academic and formal writing. As an example of passive voice in historical context, cities shaping due to car culture could be described as: 'A rethinking of the spatial layout of cities was led by the acquisition of automobiles.'