I am always eager to do experiments, especially chemistry ones. It's 21 to work with test tubes and beakers , even though sometimes my efforts end in failure. Experiments were fun for me 22  a recent accident. The accident happened when I was heating a big test tube with an alcohol burner , chatting to my partner. All of a sudden, the tube cracked. Even though I jumped from my seat when I heard the crack, the hair on my forehead was burnt as I was leaning too close to the test tube. 23 I had no time to be sad about my hair: the liquid in the test tube poured onto the table and caught fire. I'd never 24 anything so bad! My mind went blank for a moment. Then I quickly covered the fire with a damp cloth to put it out. The teacher told me that the test tube broke in half at the bottom because we didn't dry it properly before 25 it. We calmed down and did the experiment, again. But our hearts were still 26 rapidly even after we walked out of the lab. But my bad luck didn't end there! Since all our 27 was focused on the flames while we were in the lab, I didn't see the liquid falling onto my trousers. During the following class, I felt a pain in my leg. Soon it became more and m6re painful and I touched the area with my fingers, 28 to make things better. But to my great 29 , the material of my trousers turned into powder! 'Vitriol ! ! ! The terrible word came into my mind. I rushed out right away to wash and examine my poor skin. 30 , it was not a serious injury. After changing my trousers I thought it's very important to have a serious attitude in chemistry class. Doing scientific experiments as a learner is no laughing matter. 21. A. exciting    B. moving                    C. dangerous      D. difficult 22. A. but               B. except        C. besides              D. until 23. A. Because           B. Instead              C. But                   D. Or 24. A. felt               B. heard                      C. experienced    D. imagined 25. A. boiling       B. holding                C. heating                D. cooking 26. A. striking             B. beating                C. knocking       D. hitting 27. A. effort              B. sense           C. attention         D. spirit 28. A. failing              B  imanaging            C. trying          D. planning 29. A. disappointment  B. joy             C. surprise       D. comfort 30. A. Luckily      B. Obviously              C. Unexpectedly          D. Generally