解析：　根据上文可知是我的这种看到事物积极的一面的"态度"使我能够继续我的生活旅程。

　　答案：　C

　　19．A.strength B．knowledge

　　C．chance D．way

　　解析：　积极的生活态度给了我无穷的"力量"让我继续我的生活旅程。

　　答案：　A

　　20．A.hurry up B．speak up

　　C．help out D．move on

　　解析：　根据continue my journey可知积极的生活态度鼓励我在遇到困难时继续"前进"。

　　答案：　D

　　Ⅱ.阅读理解

　　Just in time for National Popcorn Day，a new study shows that people in what's now Peru were eating the snack about 2,000 years earlier than we thought.

　　Coastal peoples were preparing corn­based foods up to 6,700 years ago，according to analysis of remains of the ancient corn recently discovered at the Paredones and Huaca Prieta archaeological sites on Peru's northern coast.

　　Previously，evidence of corn as a food about 5,000 years ago had mostly come from what are called microfossils-microscopic remains that do not offer information on the size and shape of the corncobs (玉米棒)．But the new­found corn remains revealed a lot，via radiocarbon dating and other tests.

　　The people who lived in Paredones and Huaca Prieta probably cooked corn in several ways：Wrapping a corncob and resting it on coals，roasting a corncob directly over a flame，or cooking a corncob in an earthen oven.In this culture，corn was a delicious food or a minor supplement to the diet-archaeological evidence shows they did not eat it in large amounts.

Corn was first grown in Mexico about 9,000 years ago from a wild grass called teosinte，according to Piperno，whose research has been published in the journal Proceedings of the National Academy of Sciences.A few thousand years later，corn was brought to South America，where farmers bred the plant crop into hundreds of varieties.