Complex sentence: From 1898 to 1910 he studied at and was expelled from a gymnasium (a type of German secondary school) under unclear conditions, and afterwards continued his studies on his own in Berlin, Paris, and Italy.
Split into simpler sentences: From 1898 to 1910 he studied at, and was expelled from, a gymnasium (a type of German secondary school) under unclear conditions. Afterwards, he continued his studies on his own in Berlin, Paris, and Italy.