Meaning: 'Have found' means that the studies have discovered or established something, specifically that there is a correlation between childcare enrolment and maternal employment rates.

Wrong options:

• are finding: This option suggests an ongoing action, which does not fit the context since the studies have already been completed and their results are being reported.
• found: This is the simple past tense, which does not convey the ongoing relevance of the findings as effectively as the present perfect tense does.
• have yet to find: This implies that the studies have not yet discovered the information, which contradicts the context that states findings have already been made.

Correct answer: has been shown

Explanation: The phrase 'has been shown' is in the present perfect passive voice, which is suitable here as it indicates that the evidence regarding child poverty's impact on outcomes has been established and is still relevant. This fits well with the context of discussing established research findings.

Meaning: 'Has been shown' means that research has demonstrated or proven that child poverty is a significant factor affecting children's outcomes.

Wrong options:

• is shown: This option is in the present simple tense, which does not convey the established nature of the findings as effectively as the present perfect does.
• was showing: This option suggests an ongoing action in the past, which does not fit the context of established research findings.
• showed: This is the simple past tense, which does not emphasize the ongoing relevance of the findings as the present perfect does.

Correct answer: enter

Explanation: The verb 'enter' is appropriate here as it indicates the action of mothers starting or joining the workforce. This fits grammatically and contextually with the sentence, which discusses mothers moving into paid employment.

Meaning: 'Enter' means to begin or start a new phase, in this case, referring to mothers starting their employment.

Wrong options:

• enact: This means to make a law or regulation, which does not fit the context of mothers joining the workforce.
• enrol: This typically refers to signing up for courses or programs, not applicable in the context of employment.
• enlist: This usually means to join the military or a cause, which is not relevant to the context of entering the workforce.

Correct answer: through

Explanation: The preposition 'through' is suitable here as it indicates the means by which extra revenues are generated, specifically through income tax. This aligns well with the context of discussing financial implications.

Meaning: 'Through' means by means of or via, indicating that income tax is the method by which extra revenues are generated.

Wrong options:

• within: This suggests being inside something, which does not fit the context of generating revenues through a process.
• by: While this could work, it is less specific than 'through' in indicating the means of generating revenue.
• throughout: This implies a sense of all over or during the entire time, which does not accurately convey the specific means of generating income tax.