高中英语选修Book7unit4同步检测

Unit4 同步检测 Ⅰ.阅读理解 A Imagine you are on a cold mountain with steep rocks around.As you climb higher，the air gets thinner and the sun’s rays stronger.Just before you reach the snowline，you find what you came for—a small white flower，the edelweiss(火绒草)，which only grows in alpine(高山的) areas. Plants face many challenges living in alpine areas，and only 200 kinds of plants can grow there.Plants rely on oxygen，water，and sunlight to make their own food through the process of photosynthesis(光合作用)．The alpine means less CO2，which makes the process more difficult.It also brings plants closer to the sun.The sunlight is so strong that it can burn a plant’s leaves.There is little water here，so the soil is dry and rocky.You also won’t find high trees because the cold wind would blow them over! Alpine plants have advantages that help them survive the bad conditions.Like all alpine plants，the edelweiss stays close to the ground to avoid the wind.The cold wate