Final answer:
Correct passive voice transformations were provided for the sentences given, with clear focus on shifting the sentence focus from the action doer to the receiver of the action.
Step-by-step explanation:
Transforming sentences between active voice and passive voice is a common practice in English grammar to change the focus of a sentence. When changing sentences from active to passive voice, the object becomes the subject of the sentence, and the original subject may be added at the end of the sentence, typically following the preposition 'by'. Below are the correct transformations for the questions provided:
- The line was gone through by the pen. (Correct answer c: The line was penetrated by the pen.)
- Long ago, TV was invented. (Correct transformation: TV was invented long ago. None of the given options are correct, but option a could be corrected to say 'Long ago, someone invented TV'.)
- Potato sells cheap. (Correct transformation: Cheap potatoes are sold. However, the given options do not reflect the correct passive voice construction, so none are correct.)
- I helped him. (Correct answer a: He was helped by me.)
It's important to note that when using passive voice, the meaning of the sentence remains the same but the focus changes from the doer of the action to the object receiving the action. However, passive voice can sometimes make sentences vague or wordy, so it is often best used when the doer of the action is unknown or less important than the action itself.