1.Recycling is becoming an increasingly viable option for waste disposal.
(A)controversial adj. 有争议的；有争论的
(B)dirty adj. 下流的，卑鄙的；肮脏的；恶劣的；暗淡的
(C)feasible adj. 可行的；可能的；可实行的
2.With an area of some 9,355,000 square miles and shaped like a huge,upside-down triangle,North America is third in size among the world's seven continents.
(A)inverted adj. 倒转的，反向的
(B)imaginary adj. 虚构的，假想的；想像的；虚数的
(C)striped adj. 有条纹的；有斑纹的
3.The North American fur trade waned in the early 1800's mainly due to the diminishing number of fur-bearing animals.
(A)staggered adj. 错列的；吃惊的
(B)ceased v. 停止（cease的过去式及过去分词形式）；中止；中断
(C)declined v. 下降；拒绝；衰退（decline的过去分词）
4.In the period between 1941 and 1946,labor leader John L.Lewis called at least nine walkouts of his 400,000 soft-coal miners in order to win new contracts.
(A)meetings n. 会议，集会，会见（meeting的复数形式）
(B)strikes n. [劳经] 罢工；攻击（strike的复数）
(C)outings n. 远足；短途旅游；体育比赛
5.The Cheyenne Indians were considered spectacular riders and fierce warriors.
(A)hunters n. [林] 猎人（hunter的复数
(B)defenders n. 后卫；防御者（defender的复数
(C)fighters n. 战士（fighter的复数）；[航][军] 战斗机；铁骑无人机操控理论
6.The venom of coral snakes is expecially potent and the mortality rate among humans who have been bitten is high.
(A)rattles vt. 使发出咯咯声；喋喋不休；使慌乱，使惊慌
(B)teeth n. 牙齿
(C)poison vt. 污染；使中毒，放毒于；败坏；阻碍
7.The conservation research project will concentrate on wildlife habitats in the forest.
(A)tropical adj. 热带的；热情的；酷热的
(B)wilding adj. 野生的；未驯服的
(C)regional adj. 地区的；局部的；整个地区的
8.At the zenith of her career in the 1930's Dorothy Thompson was one of the best known journalists in the United States.
(A)completion n. 完成，结束；实现
(B)pinnacle n. 高峰；小尖塔；尖峰；极点
(C)outset n. 开始；开端
9.A playwright of note,Cornelia Otis Skinner was also the author of witty essays and light verse.
(A)humorous adj. 诙谐的，幽默的；滑稽的，可笑的
(B)lengthy adj. 漫长的，冗长的；啰唆的
(C)practical adj. 实际的；实用性的
答案：CACB CCBB A
详解：
1.viable
adj. 可行的；能养活的；能生育的
Well, it depends what one understands by "viable".
嗯，这取决于怎么理解“可行的”。
2.upside-down
adj. 颠倒的；乱七八糟的
This strikes me as an upside-down way of looking at things.
这种倒置的看待事物的方式，让我深受触动。
3.waned
n. 衰退；月亏；衰退期；缺损
However, it's not for everyone and I was concerned that, not surprisingly, use of the pedal machine decreased gradually over the one month trial period as enthusiasm waned.
不过，并非人人适合，而且我担心经过一个月的尝试后，员工对这种机器的激情会慢慢消失殆尽，这一点都不令人意外。
4.walkouts
n. （美）罢工；退出会场；谈恋爱
The Visteon sit-ins led to pickets of Ford dealerships and the threat of walkouts at Ford factories.
伟世通的静坐抗议引起了福特经销商的罢工，福特工厂也受到罢工威胁。
5.warriors
战士
We were no warriors but prisoners.
我们不是战士而是囚犯而已。
6.venom
vt. 使有毒；放毒
The infection or venom from the bite could kill them.
这一口带来的感染和毒液就可能杀死我的羊。
7.wildlife
adj. 野生动植物的
Hunters are barred from wildlife sanctuaries.
野生动物保护区内禁止狩猎。
8.zenith
n. 顶峰；顶点；最高点
Obama will be the zenith of black America for as long as he lives.
奥巴马毕其一生都将成为美国黑人运动成就的顶点。
9.witty
adj. 诙谐的；富于机智的
She is a witty talker.
她说话很有风趣。