about however/therefore in sentences

0Fiorentina-Lazio02br
00The Viola need to get back to winning ways this weekend if they intend on defending their fourth place in Serie A from the high-flying Roma. The Giallorossi might be given a helping hand by their city rivals Lazio who01b00, however,02b00 have not done too well when playing away from the Olimpico this season (2-5-6). Only Juventus have done better than Fiorentina at home (12-0-1), 01b00therefore02b00 the Tuscan sides are more than favourites to take all three points against this Lazio side. 01b00However,02b00 recent matches between these two teams at the Artemio Franchi stadium have almost all gone in favour of Lazio (0-2-3), so the Biancocelesti can be considered as Fiorentina’s black sheep.02br
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001.can i rewrite it to be 01b00howerver, who have not done too well02b02br
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002.therefore without 01b00,02b00?02br
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003.generally, i will often see the word 01b00However 02b00preceded sentences. whether it doesn't in the preceding position of sentences what its meaning?02br
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00thank you very much0-