21. To power their inventions, people have made use of natural energy sources, _______  coal, oil, water, and steam. A. in addition to             B. as                            C. and they use         D. such as 22. ________ excellent art museums, Moscow has a world-famous baler company. A. Because of                  B. In spite of              C. In case of              D. In addition to 23. Alex cannot express himself clearly and correctly in writing. He will never advance in his job ________ he improves his language skills. A. otherwise                    B. if                             C. only if                    D. unless 24. ________ there was no electricity, I was able to read because I had a candle. A. Unless                         B. Even though         C. Even                      D. Only if 25. A fire must have a readily available supply of oxygen. ________ it will stop burning. A. Consequently             B. Furthermore         C. Otherwise             D. However 26. I studied Spanish for four years in high school. ________, I had trouble talking with people when I was traveling in Spain. A. Therefore                                                        B. On the other hand C. Moreover                                                        D. Nevertheless 27. I am afraid that the company is in deep trouble. ________, we are going to make some people redundant. A. Therefore                B. However                  C. But                            D. And 28. I like to keep the windows open at night no matter how cold it gets. My wife, ______, prefers a warm bedroom with all windows tightly shut. A. nevertheless               B. consequently        C. on the other hand            D. moreover 29. Some fish can survive only in salt water, ________ other species can live only in fresh water. A. whereas                       B. unless                    C. if                             D. since 30. ________ Jason because famous, he has ignored his old friends. He shouldn’t do that. A. If                                  B. Ever since             C. Even though         D. Due to 31. We’re going to lose this game ________ the team doesn’t start playing better soon. A. if                                  B. unless                    C. although                D. whereas 32. Jack insisted that he didn’t need any help, ________ I helped him anyway. A. and                               B. so                           C. besides                  D. but 33. Florida is famous for its tourist attractions. Its coastline offers excellent white sand beaches. ________, it has warm, sunny weather. A. Otherwise                                                       B. Furthermore C. Nevertheless                                                  D. On the other hand 34. The flowers will soon start to bloom ________ winter is gone and the weather is beginning to get warmer. A. even if                         B. now that                C. so                           D. even though 35. Only if you promise to study hard ________ to tutor you. A. will I agree                  B. agree I                    C. I agree                    D. I will agree