Why are some bodies of water in russia unnavigable for part of the year

The answer is "Because they are frozen". The temperature in Russia drops during the winter, thus freezing lots of bodies of water.

within these regions are all the major types of biomes in the world. a biome is a community of animals and plants spreading over an extensive area with a relatively uniform climate. some diverse biomes represented in north america include desert, grassland, tundra, and coral reefs.

i need more info to answer