The lead-in poem or exposition to each chapter encapsulates the substance of the discussion and is crucial to an incisive understanding of the thesis.

每章开篇部分的引诗或引述囊括了该章的精华，对深入理解把握论文有重要意义。

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Left untreated, such issues can lead to high dropout rates, substance abuse, violence and suicide, the third-leading cause of death in adolescents.

WSJ: Will Students Take a Mental Health Test?

The scheme at La Moye targets behaviour that can lead again to crime, such as alcohol and substance misuse.

BBC: Jersey prison programme gets 'good feedback'

The projects, led by Grand Challenges Canada, will tackle issues that can lead to mental illness, such as alcohol and substance abuse, as well as delivering solutions like counselling and health promotion.

BBC: Mental health: Global effort sought