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An explanation of this technique probably takes more time than the actual exercise , but once an instructor tries it , the value of dilemma lessons is evident . If a target is used , only paper bullseye or clay ( for shotgun ) targets are to be used for the required course . To set back plant succession , wildlife managers may use fire , but they can also use mechanical means such as discing . Protein structure , nucleic acid structure , enzyme mechanisms , the phenomena underlying cellular behavior , excitable phenomena in nerve , muscle and visual cells , and integrative neural phenomena all have been subject to intense biophysical study . The translator may quietly translate while you teach , if it does not disrupt the class .