Each of the following sentences needs either a comma or a semicolon. Put in the necessary punctuation.

1. Many companies make sugar-free soft drinks, which are flavored by synthetic chemicals the drinks usually contain only one or two calories per serving.

2. Mr. Leyland played the viola professionally for many years and he now conducts a community orchestra.

3. The crab grass was flourishing but the rest of the lawn, unfortunately, was dying.

4. The hill was covered with wildflowers it was a beautiful sight.

5. As I turned around, I heard a loud thump for the cat had upset the goldfish bowl.

6. The artist preferred to paint in oils he did not like watercolors.

7. The house was clean, the table set, and the porch light on everything was ready for the guests' arrival.

8. He looked carefully in the underbrush but he failed to notice the pair of green eyes staring at him.

9. The foundations of the house had been poured but, to his disappointment, nothing else had been done because of the carpenters' strike.

10. The computer could perform millions of operations in a split second however, it could not think spontaneously.

11. I thought registration day would be tiring but I didn't know I'd have to stand in so many lines.

12. The dog, growling and snarling, snapped at me I was so frightened that I ran.

13. The snowstorm dumped twelve inches of snow on the interstate subsequently, the state police closed the road.

14. Professors are supposed to be absent-minded and I've seen plenty of evidence to support that claim since I've been in college.

15. The suspect said that he had never met the victim however, the detective knew that he was lying.

16. In the first place, it was snowing too hard to see the road in the second place, we had no chains.

17. I have read Soul on Ice but I have not read The Invisible Man.

18. San Francisco is my favorite city in fact, I plan to spend two weeks there this summer.

19. The quarterback made a brilliant pass and the end crossed the goal line for the winning touchdown.

20. Large supermarkets fascinate me I can find everything from frozen chow mein to soybean flour in one place.

21. Ron and Mike were both in English class this morning they gave an interesting presentation on their research.

22. The obstacles are not insurmountable but they are real and formidable.

23. Riding a bicycle is excellent exercise I ride mine every day.

24. I am not interested in a trip to Asia this year however, I would like to go to Europe.

25. Not all highly educated people enjoy traveling, but many world travelers are particularly well educated.

26. Jack worked overtime to pay off his education debts at least, that was his explanation for his long hours.

27. Katherine has given up smoking about five times but she cannot seem to break the habit.

28. His work may be almost totally forgotten but he would certainly be surprised to see how much current scholarship simply echoes his ideas.

29. Our dog seems to have a built-in alarm clock he wakes us up at exactly the same time every morning.

30. The passengers on the plane were initially alarmed by the loss of altitude but the pilot and the crew kept them calm.

31. I realized at once that something was wrong I was not, however, the only person who was concerned.

32. I had to complete the assignment by Friday otherwise, I would have failed the course.

33. Ralph decided to be a chemist but he changed his mind after taking Chem. 121.

34. I finished reading The Nation and then I went to bed.

35. We always go to the mountains in the fall they are at their prettiest at that time of year.

36. Tim went to the candy store quite often the clerk even knew his name.

37. Criticism of capitalist expansionism does not surface in most discussions of the worldwide ecological crisis indeed, proposed solutions rarely deviate from a basic message of further technological "progress."

38. The president has pledged to cut taxes repeatedly and the public has responded enthusiastically.

39. The office was closed consequently, I could not pay my bill.

40. The air was beautifully clear it was a lovely day.