The following selections have topic sentences (main ideas) that may appear at any place within the paragraph. Identify the topic sentence of each paragraph by choosing the answer with correct sentence number. 1 Scientists have learned that the way we view exercise strongly influences our performance. 2 Research on Russian weight lifters , for example , demonstrated that if they were told the weights were heavy , they perceived an exercise to be more difficul t. 3 If they were told the weights were light , then they considered the exercise easier. 4 Another example is the weight lifter who kept failing to break a record. 5 He finally succeeded after his trainer told him the weights he was lifting were not as heavy as they in fact were.