16. Polar winters are length, dark, and cold enough to kill most plants

17. The remains of very ancient wood have turn into coal.

18. In 1893, Henry Ford built his first car engine in he home workshop in Detroit

19. Armies of laborers toiled for eight year to build the Erie Canal.

20. Some of the stars in the closing stages of their lives becomes white dwarfs.

21. The normally force of gravity at the Earth’s surface is called Ig

22. Edward McDowell is remember as the composer of such perennial favourites as “To a Wild Rose.”

23. Because he is gravitationally bound to the Milky Way, the Andromeda galaxy is currently approaching Earth.

24. CAT scanners are used not only for detecting conditions but also for observation the effects of therapy.

25. The chain of rider stations along the way were crucial to the success of the Pony Express.

26. The functional relationship between the brain’s two hemispheres has been a major focus of much studies neuropsychology

27. The Great Salt Lake is the remnant of a vast inland seas.

28. A desire to eradicate irregular spellings in English can being traced back to the six tenth century

29. Jade con actually refer to either the leas common and more valuable jadeite and the more common and less valuable nephrite

30. The number of electrons in an atom match the number of charged particles, or protons

31. The neocortex becomes progressive more developed in the more advanced mammals

32. During their first attempts as a songwriter, George Gershwin diligently continued study the piano, harmony, theory, and orchestration.

33. Alexander Graham Bell was twenty-nine when him was granted a telephone patent in 1876. 

34. Early television sets such as the RCA Victor model had small screens but containing a mass of additional components.

35. A huge amount of immigrants passed through the Great Hall on Ellis Island between 1892 and 1954.

36. The cliff dwellings in Mesa Verde were build in the thirteenth century by Natom Americans who farmed the green plateau.

37. The poet Walt Whitman was an easy recognized figure with his long, white bear! and wide-brimmed hat.

38. The sand dollars are a distinctive group of sea urchins that have adapt especially to lie on sandy shores

39. Someone who personifies the “American Dream” are Andrew Carnegie, who immigrated to the United States from Scotland without money and male millions in the steel industry.

40. The Nez Perce lived peacefully with the trappers and traders who travelled theirs lands until the discovery of gold in 1860 brought miners and settlers into the region.