题目：Climate of the past
1. Ice layers can provide information of the past climate, top layers are recently produced and bottom of the layers are formed for many years.
2. Air bubbles in the ice can yield climate information as well. By investing the gases in the bubbles, the correlation and connection of carbon dioxide and temperature are revealed.
3. Some sea sediments can also tell information of the climate.
3.sensitive to =responsible for
1. There are two conditions of becoming flightless. First is no need to migrate to warm conditions. Second is no predators.
2. South America has a special bird which has no predators, this result flightless.
3. Flightless has advantages. Flightless birds can feed on plants due to their digestion system which is so heavy for flight birds
4. Flightless birds have larger eggs which can provide embryo more nutrients
5. Why most flightless birds didn't evolve to hands? Maybe due to their beak which can manipulate objects. However, some birds evolve to hands and paws.
题目：Some qualities of a good trout stream
1. Some streams have common qualities for trout ( a kind of bird)
2. Cool-cold water
3. Smooth-slowing water
4. Cover and shelter
5. Abundant insects
6. Areas for building nests
7. Conclude all the conditions for trout