16. Beer is the most popular drinks among drinkers,____ overall consumption is significant.
A)whose B) which C) that D) what
17. The professor could hardly find sufficient grounds ___ his arguments in favor of the new theory.
A)to be based on B) to base on C) which to base on D) on which to base
18. Living in the western part of the country has its problem, ___ obtaining fresh water is not the least.
A)with which B) for which C) of which D) which
19. The hours ____ the children spend in their one-way relationship with television people undoubtedly affect their relationship with real-life people.
A)when B) on which C) that D) in which
20. Agriculture was a step in human progress ___ which subsequently there was not anything comparable until our own machine age.
A)to B) in C) for D) from

语法参考答案
16. A) 题意：啤酒是饮酒者最喜爱的饮品。
解析：此句从句的主语和先行词间的关系属从属关系，故选A。
17. D) 题意：教授难以找到充足的论据来证明他赞成新理论的论点。
解析：此句中的先行词在从句中作base on的宾语,此处考察的是名词+介词+which/whom+动词不定式结构的定语从句。
18. C) 题意：生活在该国家的西部地区有其自身的问题，获取饮用水就是一个难题。
解析：非限定性定语从句与其修饰的先行词之间是从属关系，故选C。
19. C) 题意：孩子们与电视人物之间的关系是单向的，他们花在这种关系上的时间无疑会影响他们与现实生活中人们间的关系。
解析：从句中缺直接宾语，故选C。
20.A) 题意：农业是人类发展进程中的一步，在我们的机器时代到来之前，任何事物都不能和它相提并论。
解析：先行词作定语从句中短语be comparable to(把…比作)的宾语，故此处应为to which。