Provide correct tense of the verb

Provide correct tense of the verb
1. 1 While he ____ 1.1 (take) a bath, Archimedes _____ 1.2 (discover) the principles of density and buoyancy.

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1. 2 While he ____ 1.1 (take) a bath, Archimedes _____ 1.2 (discover) the principles of density and buoyancy.

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2.1 When Benedictus, a French scientist, ______ 2.1 (work) in his laboratory, he _____2.2 (drop) a glass of bottle which had some plastic inside – and invented safety glass.

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2.2 When Benedictus, a French scientist, ______ 2.1 (work) in his laboratory, he _____2.2 (drop) a glass of bottle which had some plastic inside – and invented safety glass.

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3.1 Columbus _____ 3.1 (arrive) in America while he ____3.2 (try) to reach the Far East.

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3.2 Columbus _____ 3.1 (arrive) in America while he _____3.2 to reach the Far East.

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4.1 Alexander Fleming _____ 4.1 (discover) penicillin by accident while he _____4.2 (look) some old experiments.

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4.2 Alexander Fleming _____ 4.1 (discover) penicillin by accident while he _____4.2 (look) some old experiments.

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5.1 While Hiram Bingham ______ 5.1 (climb) in the mountains in Peru in 1911, he ______5.2 (discover) the lost city of Machu Picchu.

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5.2 While Hiram Bingham ______ 5.1 (climb) in the mountains in Peru in 1911, he ______5.2 (discover) the lost city of Machu Picchu.