I have a new situation: Tim and Jeb were both studying chemical engineering. At a certain point in time, Jeb started studying chemicals that are not harmful for the environment, while Tim started learning about chemicals that were once used, but now are known to be harmful for the environment. But I can use this background: Many chemicals that were once commonly used were later found out to be harmful to the environment , to human health, or both. The element lead was once a common additive to gasoline and to paint. Plumbing pipes were once typically made of lead. Only since the 1970s has the danger of lead become apparent. It causes brain damage and small children (who often chewed on objects painted with lead-based paint) are particularly susceptible. The use of lead in gasoline, paint, and plumbing pipes is now banned and new materials are being developed to replace the hazardous lead components. What is an answer for this question: Which student studied more about gasoline?
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Answer: Tim

I have a new situation: Timber village started a channelization process by draining all the swamps near their village. Hill village situated 10 miles to the south, left their swamps untouched. But I can use this background: Ecologically, the expansion of drainage systems has had tremendous negative effects. Hundreds of thousands of wetland species experienced significant population declines as their habitat was increasingly fragmented and destroyed. Although market hunting within the Central Flyway was a contributing factor in the decline of many waterfowl species' numbers in the early decades of the twentieth century, loss of breeding habitat to agricultural expansion is certainly the most significant. Early maps of midwestern states depict many lakes and marshes that are either nonexistent or significantly reduced in area today. Channelization, a related process of concentrating and facilitating the flow of water from agricultural areas, also contributed to this degradation. What is an answer for this question: Which village converted less swampland into farmland?
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Answer: Hill

I have a new situation: Two rivers spring from the same mountain. Olt was a fast moving river, while Mures river was slow moving and deep. Both rivers are very important for the local economies. But I can use this background: The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater biodiversity than the slow moving water of pools. These distinctions form the basis for the division of rivers into upland and lowland rivers. The food base of streams within riparian forests is mostly derived from the trees, but wider streams and those that lack a canopy derive the majority of their food base from algae. Anadromous fish are also an important source of nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution and introduced species. A dam produces negative effects that continue down the watershed. The most important negative effects are the reduction of spring flooding, which damages wetlands, and the retention of sediment, which leads to loss of deltaic wetlands. What is an answer for this question: Which river had a food source mostly derived from the trees?
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Answer:
Olt