tailieunhanh - The official guide to the new toefl ibt part 11

Chapter 1 provides an overview of the test, information about test scores, an introduction to the on-screen appearance of the different parts of the TOEFL iBT, along with general test-taking suggestions | ffl V u to IB D0 J D TJ There are adaptations that increase the amount of forward thrust as well as those that reduce drag. Again these fishes are the envy of engineers. Their high narrow tails with swept-back tips are almost perfectly adapted to provide propulsion with the least possible effort. Perhaps most important of all to these and other fast swimmers is their ability to sense and make use of swirls and eddies circular currents in the water. They can glide past eddies that would slow them down and then gain extra thrust by pushing off the eddies. Scientists and engineers are beginning to study this ability of fishes in the hope of designing more efficient propulsion systems for ships. According to the passage one of the adaptations of fast-swimming fishes that might be used to improve the performance of ships is these fishes ability to swim directly through eddies make efficient use of water currents O cover great distances without stopping O gain speed by forcing water past their gills The muscles of these fishes and the mechanism that maintains a warm body temperature are also highly efficient. A bluefin tuna in water of 7 C 45 F can maintain a core temperature of over 25 C 77 F . This warm body temperature may help not only the muscles to work better but also the brain and the eyes. The billfishes have gone one step further. They have evolved special heaters of modified muscle tissue that warm the eyes and brain maintaining peak performance of these critical organs. 10. According to paragraph 9 which of the following is true of bluefin tunas O Their eyes and brain are more efficient than those of any other fish. O Their body temperature can change greatly depending on the water temperature. O They can swim in waters that are much colder than their own bodies. O They have special muscle tissue that warms their eyes and brain. 94 THE OFFICIAL GUIDE TO THE NEW TOEFL ÍBT mtr4ũa tai ID Again supersonic jets have similar features. Because they are always .