句子一：
原文：Those with degrees from elite universities catch up fairly quickly to where they otherwise would have been if they had graduated in better times； it is the masses beneath them that are left behind.
解析：
主句：Those with degrees catch up fairly quickly.
宾语从句：where they otherwise would have been.
虚拟条件状语从句：if they had graduated in better times.
强调句：It is the masses that are left behind.
介词短语：with degrees作后置定语修饰Those。
句子二：
原文：Instead, the best strategy is to use the agent a
解析：
该句不完整，缺少宾语，可能是讨论使用代理（agent）的策略。
句子三：
原文：There are also companies like Acquisio, which analyzes advertising performance across multiple channels like Adwords, Bing and social media and makes adjustments or suggestions about where advertising funds will yield best results.
解析：
主句：There are also companies like Acquisio.
定语从句：which analyzes advertising performance across multiple channels.
并列结构：like Adwords, Bing and social media.
目的状语：and makes adjustments or suggestions.
宾语从句：about where advertising funds will yield best results。
句子四：
原文：Stronger public-health systems would help fight such diseases as tuberculosis, which reduces global GDP by $ 12 billion a year, and malaria, which takes an even bigger toll.
解析：
主句：Stronger public-health systems would help fight such diseases.
定语从句：as tuberculosis, which reduces global GDP by $ 12 billion a year.
并列结构：and malaria, which takes an even bigger toll。
句子五：
原文：Today小编为2020到2021考研的同学整理解析历年考研英语真题中的长难句.
解析：
该句为介绍性句子，说明作者为考研学生整理长难句解析的目的。
句子六：
原文：小编为大家带来2020考研英语备考：历年试题经典长难句+解析（3），为你考场作答拨云见雾愿各位考生在考试中得到满意的分数.
解析：
该句为介绍性句子，说明作者为考研学生提供历年试题中的长难句解析。
句子七：
原文：2021考研已经进入紧张的冲刺阶段，考生务必要重视考研英语的复习. 在考试中考生会遇到长难句的阻碍，为了帮助大家掌握考研英语长难句!甘肃中公教育给大家整理了历年考研英语经典长难句及详细解析，供大家参考学习使用.
解析：
该句为介绍性句子，说明作者为考研学生整理长难句解析的目的。
以上解析基于提供的参考信息，并进行了简化以便于理解。对于更深入的理解和记忆，建议结合具体的语境和语法知识。