（改1）The oak tree, the average life span of which is about 600 years, is credited to be the undisputed king of the western world which can grow to the height of more than 40 meters.
改1：开头要把oak tree整体的印象写出来，争取把每个部分的特点都涵盖在内。
The oak tree, the king of the western world, has the majesty look with its thick trunk and dense leaves which fall away in winter and then appear in the next spring—a cycle repeating for about 600 years.
The oak tree has a deep, broad root system to draw water and minerals from the soil, and transmit these nutrients from the root to the rest of the tree. Above the ground, the thick trunk covered with dark, brownish bark grows straight upward, and branches out toward the top, providing shade for travelers and animals in the heat of the day. （改2）On each branch, leaves are spirally arranged with rounded lobes along the edges. The chlorophyll in leaves plays an important role in undertaking photosynthesis, by which the oak tree can obtain energy from the sunlight and turn water and carbon dioxide into food. （改3）In autumn, the oak tree stops producing this kind of substance, and the leaves then turn orange or bronze, after which they fall away and are replaced by new leaves in the next cycle.
改2：光合作用的解释不够清晰，简练
On each branch, lobed leaves are spirally arranged where photosynthesis converts carbon dioxides and sunlight absorbed by chlorophyll into food, which is then passed down to the rest of the tree.
改3：对于叶子颜色的变化+季节更替可以换更好的表达方式
The oak tree stops producing chlorophyll in autumn, so the leaves loses its green but puts on more red, orange and bronze. Winter will see the whole tree falls asleep with bare branches—waiting for life to revive in the next spring.
Oak trees start blooming when they reach the age of 20. The formation of blooms depends on weather conditions and different tree species. Roughly speaking, white oaks bloom in March, two weeks earlier than red oaks, and they are all in full blossom in April. Oak trees bear both male and female flowers, which means they self-pollinate. （改4）The male flowers hanging in clusters produce pollen, while inconspicuous female flowers hidden among twisted branches produce seed—a small oval nut called acorn. The acorn usually contains a hard seed, enclosed in a tough, leathery shell, and borne in a cup-shaped carpel. It usually takes 1 to 2 years for acorns to mature before dropping from the tree, depending on the climate.
改4：对于acorn形成以及成熟的过程的解释不够清晰，简练
The male flowers hanging in clusters produce pollen, and the seeds—the acorns start to develop in those inconspicuous female flowers hidden among twisted branches. Acorns usually take one to two years to mature before dropping from the tree, which depends on the climate.
