单项选择题

Science is based upon observation. However, observation 1 is not science. Scientists generally state a problem. Then 2 guides them in their observations. But without observation people generally are not 3 of a problem. This then raises a question 4 comes first, the observation or the problem. Curiosity awakens a 5 for observation. Observation will usually 6 specific questions in the mind of a scientist. 7 his curiosity he begins to make observations. 8 , he formulates a specific statement that can be tested. This statement is called a hypothesis. It is the starting point for an experiment.
9 experimenting, the scientist tries to show or prove that the hypothesis is true 10 false. He must use good 11 to create an experiment that 12 the problem. The experiment must produce 13 information or data. The data gathered during the experiment are observations.
Observations can be made directly and indirectly. For indirect observation, instruments are often used. 14 instruments used by modem scientists are quite simple, others are very 15 .
To complete his experiment, the scientist must state his observations 16 numerical form. This means that he has to make measurements. With the results from 17 he can make more exact comparisons or descriptions to 18 his hypothesis. The results of a scientific experiment 19 on a logical hypothesis can often 20 a better understanding of the world and the universe.

A.convenient
B.comfortable
C.compound
D.complex
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