Tham khảo tài liệu 'delta's key to the next generation toefl test part 16', ngoại ngữ, toefl - ielts - toeic phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 13 Coherence 6. Look at the four squares Q. Q. 0 and Q which indicate where the following sentence could be added to the passage. Where would the sentence best fit The front end of the body bends less than the back end so each undulation increases in size as it travels along the body. We can understand how fish swim by studying the motion of a very flexible fish such as an eel. El The movement is serpentine with undulations moving backward along the body by alternate contraction of the muscles on either side of the eel s body. Q While the undulations move backward the bending of the body pushes sideways against the water producing a reactive force that is directed forward at an angle. 0 The movement has two components thrust and lateral force. Q Thrust is used to propel the fish forward and lateral force tends to make the fish s head deviate from the course in the same direction as the tail. This side-to-side head movement is very obvious in a swimming eel but fish with large rigid heads have enough surface resistance to minimize the lateral movement. Questions 7-10 Both the Greeks and the Romans minted coins. The Romans called the place where coins were made and stored by the Latin word moneta the ancestor of the English word money. Even after coins were developed however the world was still a long way away from our current system of money. Each city made its own coins with no common way of exchanging one type for another. Gradually traders worked out different rates of exchange. Another complication lay in the fact that for thousands of years most people did not use money for important purchases. Although the wealthier classes used money for major transactions ordinary people continued to barter for most things in their daily lives. For example workers would be paid in food clothing and shelter rather than in money. Farmers would grow food and make items for themselves trading the tiny surplus for whatever they could not make or grow. Paper money had a lot of .
