When people first began to write, they did not use an alphabet. Instead, they drew small pictures to (34) the objects they were writing about. This was very slow because there was a different picture for every word. The Ancient Egyptians had a (35) of picture writing that was called hieroglyphics. The meaning of this writing was forgotten for a very long time but in 1799 some scientists discovered a stone near Alexandria, in Egypt. The stone had been there for over a thousand years. It had both Greek and hieroglyphics on it and researchers were finally able to understand (36) the hieroglyphics meant.
An alphabet is quite different (37) picture writing. It consists of letters or symbols that represent a sound and each sound is just part of one word. The Phoenicians, who lived about 3,000 years ago, developed the modern alphabets. It was later improved by the Roman's and this alphabet is now used (38) throughout the world.

The generation gap that was so in evidence during the 60s has resurfaced, but a 2009 study showed that it was not the disruptive force. The Pew Research Center study found that 79% of Americans see major differences between younger and older adults in the way they look at the world. In 1969, a Gallup Poll found that a smaller percentage, 74%, perceived major differences.
Today, however, although more Americans see generational differences, most do not see them as divisive. That is partly because of the areas of difference. The top areas of disagreement between young and old people, according to the Pew Research Study, are the use of technology and taste in music. Grandparents are likely to have observed these differences in their grandchildren who are tweens, teens, and young adults.
If large differences between the generations exist, why don't they spawn conflict? The answer is twofold.
First, the two largest areas of difference - technology and music - are less emotionally charged than political issues. The older generation is likely to be proud of the younger generation's prowess in technology rather than to view it as a problem. As for the musical differences, each generation wants its own style of music, and the older generation generally can relate to that desire.
Second, in the other areas of difference, the younger generation tends to regard the older generation as superior to their own generation – clearly a difference from the 1960s with its rallying cry of "Don't trust anyone over thirty!". According to the Pew study, all generations regard older Americans as superior in moral values, work ethics and respect for others.

Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.
The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.
The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.
There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned today.