2. Which of the following does not move through a plant’s stomata?
A. Carbon dioxide.
B. Water vapor.
C. Oxygen.
D. Food.
3. In the title, the term Essential Scientific Process refers to
A. photosynthesis.
B. the formation of glucose.
C. global warming.
D. water getting to the roots of plants.
4. This passage is primarily developed by
A. explaining a process.
B. telling a story.
C. comparing and contrasting.
D. convincing the reader of plants’ importance.
5. Another good title for this passage would be
A. Oxygen and Carbon Dioxide.
B. Plants and Their Roots.
C. How Photosynthesis Works.
D. Why Our Earth Needs Water. 答案与题解：
1.B 前文讲到，植物产生的氧气一部分被植物自身消耗了，但植物消耗的氧气量远小于它们产生的氧气，因此可以推测这句话的意思应该是剩余的氧气对于动物以及其他生物体的生存是至关重要的。excess在句中的意思是“超额的”，与extra“额外的”意思相近。
2.D 从第三段的第一、二句得知，二氧化碳、氧气和水蒸气都能从气孔中通过，唯一一个没有提到的是food“养分、食物”，因此该题选D项。
3.A 文章通篇都在讲Photosynthesis，即光合作頌钠作用和重要性，文章结尾又重申了Photosynthesis is essential for life on our planet，因此选A项。B项是光合作用的一个部分，C、D项则毫不相干。
4.A 文章先是介绍了进行光合作用所需的原料和组织，又介绍了光合作用的过程，因此整个逻辑应该是解释过程，而不是讲故事或比较对比。D项是“向读者说明植物的重要性”，这确实是文章的一个目的，但不是文章的组织方式。
5.C 文章的主题是光合作用的基本原理，因此选项C。A、B项在文中有提及，但不是主旨，D项与本文无关。
第五篇 A Record-Breaking Rover
NASA’s Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. ____1____
On July 27, after years of moving about on Martian ground, the golf-cart-sized Opportunity had driven more than 24 miles, beating the previous record holder—a Soviet rover sent to the moon in 1973.
“This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance,” says John Callas, the Mars Exploration Rover Project Manager.
____2____ “But what is really importantly is not how many miles the rover has racked up, but how much exploration and discovery we have accomplished over that distance.”
OPPORTUNITY
The solar-powered Opportunity and its twin rover, Spirit, landed on Mars 10 years ago on a mission expected to last 3 months. ____3____
Spirit stopped communicating with Earth in March 2010, a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.
During its mission, Opportunity has captured, and sent back to Earth, some 187,000 panoramic and microscopic images of Mars with its cameras. ____4____
MARATHON ROVER
The rover doesn’t seem to be ready to stop just yet. If Opportunity can continue on, it will reach another major investigation site when its odometer hits 26.2 miles. ____5____
Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars’s ancient environment1. Opportunity’s continuing travels will also help researchers as they plan for an eventual human mission to the Red Planet.
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