Text: a book that i like very much, though i do not understand one single line in it!

Correct capitalization: A book that I like very much, though I do not understand one single line in it!

Text: teabox with 7 different flavors of tea

Correct capitalization: Teabox with 7 different flavors of tea

Text: the winners of the last edition and their teachers are now about taking part to a four-day trip to zambia, where they will join louis michel, european commissioner for development. being involved in a rich programme of visits, the students will observe and discover european actions in the field.

Correct capitalization: The winners of the last edition and their teachers are now about taking part to a four-day trip to Zambia, where they will join Louis Michel, European Commissioner for Development. Being involved in a rich programme of visits, the students will observe and discover European actions in the field.

Text: plant them in pots with at least 30 cm in diameter and make sure that there is 5-8 cm between the plants.

Correct capitalization:
Plant them in pots with at least 30 cm in diameter and make sure that there is 5-8 cm between the plants.