Duolingo English Test Practice Test 43

You can find fresh fruit and vegetables at the mar on Saturday mornings, and everything is cheap. Astronauts on the space station exercise for two hours every day to prevent their muscles from becoming we. Let's meet outside the shopping centre at half past two, and then we can wat a film together. According to the weather forecast, temperatures will fall sharply tonight, so cover your plants with a thick blan if you can. Tiny robots are now being tested in hospitals, where they carry medicine and meals between wards without ever getting tir. Before you sign the rental agreement, read every clause carefully, because hidden fe can make a cheap flat surprisingly expensive.

As cities search for cleaner sources of power, some are experimenting with small wind turbines mounted directly onto tall buildings. Unlike the huge turbines found on rural wind farms, these compact devices are designed to cope with the turbu, constantly shifting gus that swirl around skyscr. Engineers have found that placing turbines near roof edges or between two towers can actually increase the wind speed, making the design more effic than a turbine stan alone in open countryside. Critics argue that these urban install gene relatively little electricity, though suppo insist every extra source of clean power matt.

Each autumn, millions of monarch butterflies leave their breeding grounds across the United States and Canada and fly south toward a handful of forested mountains in central Mexico. What makes the journey remarkable is that no single butterfly Select…completescompletecompleting the whole round trip; the migration instead spans several short-lived generations. A butterfly born in Mexico in early spring flies north and lays eggs before dying, and its offspring continue the journey in relay, generation after generation, until autumn's butterflies, sometimes four generations removed, somehow find their way back to the very same mountain forests their great-great-grandparents left. How this route is inherited rather than learned remains only partly understood, though scientists suspect a combination of the sun's position and an internal magnetic sense Select…playsplayplaying a role. Researchers Select…tagtagstagging a small sample of wings each season to trace the route. Deforestation in Mexico and the loss of milkweed, the only plant monarch caterpillars can eat, have caused population numbers to fall sharply over recent decades. Conservation groups have responded by planting milkweed along the migration corridor and by pressing for stronger protection of the Mexican forests where the butterflies overwinter. Each cluster of overwintering butterflies can Select…numbernumbersnumbering in the hundreds of thousands, clinging together on tree branches for warmth through the cooler mountain nights.