(20 13? Jianning County Quality Inspection) If it is the experimental design of an interest group in the process of exploring the photosynthesis of green plants, please answer: (1) root according to the analysis. (1) Because the conditions of devices A and B are the same except the conditions of green plants, they constitute a group of control experiments and variable green plants.

(2) The plants in device B can carry out photosynthesis to generate oxygen, which can be supplied to the candle to burn, so the candle can burn for a long time; Device A has no plants and cannot carry out photosynthesis, so the burning time of device B is longer than that of device A..

(3) Repeat the experiment for many times to take the average value, so as to reduce the error and avoid contingency. (4) If the device B is covered with black cloth, photosynthesis will not be carried out, and the burning time of the candle will be shorter than that without black cloth. (5) In order to improve the intensity of photosynthesis, we can extend the illumination time (or "increase the concentration of carbon dioxide", "reasonable close planting" and so on). ).

So the answer is

(1) control green plants

(2) B is longer than A, and the photosynthesis of green plants in B releases oxygen.

(3) Avoid the contingency of experimental results (other reasonable answers are acceptable)

(4) shorten? Without light, green plants cannot carry out photosynthesis and release oxygen.

(5) Prolonging the illumination time (or "increasing the concentration of carbon dioxide" and "reasonable close planting". )