11.When the weather is fine, watching TV all day is not a ________ way to spend your time.
A. worth
B. sensitive
C. worthwhile
D. convenient
[解析]worth 值得的，只作表语;sensitive 敏感的，过敏的;worthwhile 值得的，作定语或表语;convenient 方便的。由句意和句中所缺成分可以知道C项正确。
[答案]C
12. Just like fingerprints, each person's DNA is ________ unless he has a twin.
A. unusual
B. normal
C. various
D. unique
[解析]句意：就像指纹一样，除非有孪生兄弟姐妹，要不然一个人的DNA也是独一无二的。unusual 不同寻常的;normal 正常的;various 各种各样的;unique 独特的，独一无二的。由句意可知D项正确。
[答案]D
13.His knowledge of French was ________ for the job, although he was not fluent in the language.
A. adequate
B. abstract
C. available
D. appropriate
[解析]句意：他的法语知识对这份工作来说足够了，虽然他法语讲得不流利。adequate 足够的，可胜任的;abstract 抽象的;available 可达到的，可获得的;appropriate 合适的，恰当的。由句意可知A项正确。
[答案]A
14.His first book is of great use for our course. But his latest one is ________ worth reading.
A. better
B. more
C. much
D. very
[解析]句意：他的第一本书对我们很有用。但他最近的这一本更值得一读。be well worth doing 很值得做某事，well 的比较级为 better，故A项正确。
[答案]C
15. Many students find ________ jobs during their summer holidays to obtain some working experience.
A. permanent
B. comfortable
C. temporary
D. stable
[解析]句意：许多学生在暑假期间找临时工作以获得一些工作经验。permanent 永久的;comfortable 舒服的;temporary 临时的，暂时的;stable 稳固的。由句意知C项正确。
[答案]C
16. The zoo worker told the visitors that in the case of a highly ________ animal, performance training is easy and not so painstaking.
A. intelligent
B. interactive
C. internal
D. initial
[解析]句意：动物园工作人员告诉游客，在碰到高智商动物的情况时，训练表演很容易，不那么费劲。intelligent 聪明的;interactive 相互作用的，相互影响的;internal 内部的，里面的;initial 开始的，最初的。由句意可知A项正确。
[答案]A
17.—What do you think of investing in today's stock market?
—There are many risks, but also many ________ gains.
A. potential
B. confidential
C. influential
D. preferential
[解析]句意：—你认为投资现今的股票市场怎么样?—有许多风险之处，但也有潜在的获利机会。potential 潜在的;有潜能的;confidential 机密的;机要的;influential 易受影响的;preferential 优先的，优待的，优惠的。由句意可知A项正确。
[答案]A
18.________， the boys were shouting and singing.
A. Happy and excited
B. Happily and excited
C. Happily and excitedly
D. Happy and excitedly
[解析]句意：既高兴又兴奋，男孩子们又喊又唱的。分析结构可知，此处用形容词作状语，表示主语 the boys 的状态，故A项正确。
[答案]A
19.After climbing up the top of the mountains, the three of them sat there, ________.
A. hungry and tiredly
B. hungrily and tiredly
C. hungry and tired
D. hungrily and tired
[解析]句意：爬到山顶之后，他们三个坐在那，又累又饿。由语境可知，此处是形容词作状语，表示主语 the three of them 所处的状态，故C项正确。
[答案]C
20.After the long journey, the Smiths returned home, ________.
A. safely but tired
B. safe but tired
C. safe and tiring
D. safely and tiring
[解析]句意：长途旅行过后，史密斯一家回来了，安全但很疲惫。由语境可知，此处应用形容词作状语，表示主语 the Smiths 的状态，故选B项。C项 tiring 不能修饰人。
[答案]B
