Answer:
The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary. In June 1914, a Serbian-nationalist terrorist group called the Black Hand sent groups to assassinate the Archduke.
Russia last czar of Russia was czar nicholas II. he was overthrown is 1917 in what is called the Russian revolution.
The word which means "can be helpful or harmful depending on the point of view" is beaver. Beaver can both have a good and a bad effect to the ecosystem. In a good point of view, beaver serves as natural filters segregating sediments from flowing to bodies of water. On the other hand, it can also cause flooding.
