SidLearn — IELTS Academic Mock Test 2

A. For centuries, rivers were treated as obstacles that cities had to control. Walls, channels and underground pipes were built to move water away as quickly as possible. This approach reduced some immediate risks, but it also separated urban residents from the rivers that shaped their settlements. In recent decades, planners have begun to reconsider whether a river should be treated only as a drainage problem. B. One reason for the change is the growing recognition that rivers perform several functions simultaneously. They can provide habitat, recreational space and routes for walking and cycling. Vegetated riverbanks can slow water during heavy rainfall, while wetlands can temporarily store excess water. These functions become particularly valuable as cities face more intense rainfall events. C. River restoration does not necessarily mean returning a river to its historical condition. In densely built areas, complete restoration may be impossible. Instead, projects may widen selected sections, replace concrete banks with planted slopes, create shallow areas for aquatic organisms or reconnect isolated wetlands. The objective is often to improve ecological and social functions without abandoning flood protection. D. Yet restoration can create conflicts. A park may attract visitors and increase the value of nearby property, but that can also contribute to rising rents. Removing a flood wall may improve public access while making residents nervous about safety. Engineers therefore increasingly work with ecologists, landscape designers and local communities rather than treating restoration as a purely technical task. E. Monitoring is another essential element. A project may appear successful immediately after construction, but ecological processes develop slowly. Researchers may record water quality, fish populations, vegetation growth and the frequency of flooding. Social indicators can include visitor numbers and residents’ perceptions of safety. F. The most durable projects tend to be adaptive. If a planted bank fails, it can be redesigned. If a footpath causes erosion, its route can be altered. Such flexibility recognises that urban rivers are dynamic systems rather than fixed pieces of infrastructure.

A. Human attention has often been described as a limited resource. Yet researchers studying attention increasingly distinguish between simply noticing something and sustaining deliberate focus. A person may notice a notification without intending to read it, for example, while sustained attention involves maintaining a goal despite competing signals. This distinction matters because modern environments contain many sources of interruption. B. Digital devices are not the only source of distraction. Open-plan offices, frequent meetings, background conversations and poorly designed workspaces can also interrupt concentration. Some interruptions are useful because they allow information to circulate quickly. Others create what researchers call attention residue: part of a person’s mental effort remains connected to a previous task after switching to another one. C. One response has been to design periods of protected concentration. In some organisations, employees reserve particular hours for tasks requiring deep work. Others use visual signals to indicate that they should not be interrupted. These measures do not eliminate communication; instead, they separate collaborative time from individual concentration. D. Physical design can contribute as well. Natural light, moderate temperature and appropriate acoustic conditions can influence comfort and concentration. However, there is no universally ideal environment. A sound level that helps one person maintain alertness may disturb another. Personal control over the environment may therefore be as important as any particular environmental setting. E. Educational institutions face a similar challenge. Students are often told to concentrate, but they may receive little instruction in how attention works. Teaching students to break complex assignments into stages, silence unnecessary notifications and plan periods of focused study can turn concentration into a practical skill rather than a vague expectation. F. Researchers caution against treating every interruption as harmful. Short breaks can restore attention, and some creative tasks benefit from movement between related ideas. The important question is not whether interruptions exist, but whether they occur at appropriate moments and whether the individual can return efficiently to the original goal. G. This perspective suggests that attention should be treated partly as a design issue. Individuals can change their habits, but schools, workplaces and digital platforms also shape the conditions under which people attempt to concentrate.

A. The spread of large-scale renewable energy has created a new engineering problem: electricity generation does not always occur when consumers need it. Solar panels produce most electricity during daylight, while demand may rise in the evening. Wind generation can also vary substantially. Energy storage is therefore becoming an important component of modern power systems. B. Batteries are the most visible storage technology, particularly for short-duration balancing. They can respond rapidly when electricity supply changes. However, batteries are not the only option. Pumped-storage hydropower uses electricity to move water uphill and later releases it through turbines. Thermal storage can retain heat for later use, while other technologies are being developed for longer-duration applications. C. Storage should not be understood simply as a container for surplus electricity. Its economic value depends on when and where electricity is needed. A battery located near a congested part of the grid may reduce pressure on transmission infrastructure. A storage facility connected to a solar farm may absorb excess daytime generation and release it after sunset. D. The environmental effects of storage technologies also require careful assessment. Batteries depend on materials whose extraction can create environmental and social pressures. Recycling systems can recover valuable materials, but collection and processing infrastructure must be developed. Hydropower storage has different impacts, including changes to landscapes and water systems. E. Another issue is market design. In some electricity markets, storage can earn revenue by buying electricity when prices are low and selling it when prices rise. It can also provide services that help maintain grid frequency. Regulations determine whether these multiple benefits can be combined efficiently. F. Longer-duration storage presents a different challenge. A system designed to cover several days of low renewable output must hold much more energy than a battery used for a few minutes. Costs, safety, efficiency and the availability of suitable sites all become more significant. No single technology is therefore likely to dominate every application. G. The broader lesson is that renewable energy expansion requires coordination between generation, networks, storage and demand. Consumers can contribute through flexible electricity use, while grid operators can improve forecasting and transmission planning. Storage is important, but it is one part of a larger system.