B4

Russia has a varied climate. Almost all of Russia is situated in the North Temperature Zone.
(present simple passive, т.к. она находится, а не она расположила)

SITUATE

B5

The climate is continental; however, the fluctuations in temperature are greater than in other European countries.
(степень сравнения)

 GREAT

B6

The extreme north is a cold bare region — the tundra. For more than six months it is buried in snow.
(present simple passive, т.к. она находится, а не она расположила)

BURY

B7

This region can be called the land of frozen rivers.
(Participle II “замёрзший”, подходит по смысловому контексту)

 FREEZE

B8

In May the temperature begins to rise. The gloomy night is succeeded by continuous daylight, when the sun does not sink/ doesn’t sink below the horizon for several months.
(present simple, т.к. это общее утверждение. это происходит всегда, регулярно.)

NOT SINK

B9

The better part of Russia is not influenced by the warm winds of the Atlantic and Pacific Oceans. There are no mountains in the north to form a barrier against the cold winds blowing from the Arctic Ocean.
(Participle I, “дующий”, подходит по смысловому контексту)

 BLOW

B10

The extreme west of Russia has a temperate climate. Thus, the summers in the Baltic are cool and the winters mild. If we go further/ farther east, the climate will become more continental.
(степень сравнения)

 FAR