Ⅰ.阅读理解
California has lost half its big trees since the 1930s，according to a study to be published Tuesday and climate change seems to be a major factor(因素)．
The number of trees larger than two feet across has declined by 50 percent on more than 46,000 square miles of California forests，the new study finds.No area was spared or unaffected，from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles.In the Sierra high country，the number of big trees has fallen by more than 55 percent；in parts of southern California the decline was nearly 75 percent.
Many factors contributed to the decline，said Patrick McIntyre，an ecologist who was the lead author of the study.Woodcutters targeted big trees.Housing development pushed into the woods.Aggressive wildfire control has left California forests crowded with small trees that compete with big trees for resources(资源)．
But in comparing a study of California forests done in the 1920s and 1930s with another one between 2001 and 2010，McIntyre and his colleagues documented a widespread death of big trees that was evident even in wildlands protected from woodcutting or development.
The loss of big trees was greatest in areas where trees had suffered the greatest water shortage.The researchers figured out water stress with a computer model that calculated how much water trees were getting in comparison with how much they needed，taking into account such things as rainfall，air temperature，dampness of soil，and the timing of snowmelt(融雪)．
Since the 1930s，McIntyre said，the biggest factors driving up water stress in the state have been rising temperatures，which cause trees to lose more water to the air，and earlier snowmelt，which reduces the water supply available to trees during the dry season.
本文是一篇调查报告。调查表明，加利福尼亚州的大树变少了，而气候变化是其中的一个主要因素。
1．What is the second paragraph mainly about?
A．The seriousness of bigtree loss in California.
B．The increasing variety of California big trees.
C．The distribution of big trees in California forests.
D．The influence of farming on big trees in California.
答案：A
解析：段落大意题。第二段中通过列举一系列数字表明，加利福尼亚州的大树减少的严重性，故A项正确。
2．Which of the following is wellintentioned but may be bad for big trees?
A．Ecological studies of forests. B．Banning woodcutting.
C．Limiting housing development. D．Fire control measures.
答案：D
解析：推理判断题。文章第三段提到了造成加利福尼亚州的大树减少的三个因素：woodcutters，housing development与aggressive wildfire control。前两个因素直接与大树的减少有关，如果能控制住，大树就不会减少；而第三个因素——控制野火的措施使得加利福尼亚州的森林里满是跟大树争夺资源的小树，初衷是为了控制野火，这是好的，实则对大树不利(好心办坏事)，故D项正确。
3．What is a major cause of the water shortage according to McIntyre?
A．Inadequate snowmelt. B．A longer dry season.
C．A warmer climate. D．Dampness of the air.
答案：C
解析：细节理解题。根据文章最后一段中的“...the biggest factors driving up water stress in the state have been rising temperatures...”可知，水不足的主要原因就是气温升高(rising temperatures)，即更加温暖的气候，故C项正确。
4．What can be a suitable title for the text?
A．California's Forests：Where Have All the Big Trees Gone?
B．Cutting of Big Trees to Be Prohibited in California Soon
C．Why Are the Big Trees Important to California Forests?
D．Patrick McIntyre：Grow More Big Trees in California
答案：A
解析：标题归纳题。本文是一篇调查报告，第一段就点出主题：California has lost half its big trees since the 1930s。后面具体分析了加利福尼亚州大树的现状、造成大树减少的原因等，故A项作为标题最合适。
