B2U3Read the passage carefully and find the topic sentence（主题句） of each paragraph and the supporting details(支持性细节 ).Paragraph 1Topic sentence: _Supporting details: 1822:1642：calculating machinethen:As time went by:1936:Paragraph 2：Topic sentence: _World Wide WebtubesSupporting details:Paragraph 3：Topic sentence: _Supporting details:communications finance _ _ _ _ _Retelling：B1U52. Divide the passage into two parts according to the given words.Part1 : Paragraph ( ) the life of Elias life he met Nelson Mandela.Part2: Paragraph ( ) the change of Elias life he met Nelson Mandela.