Hello,I think 1st is no problem,
2nd's "his",right answer is "他",in Chinese,"它" means animal or something doesn't have life.
3rd I think it would be better if you add "将"or"把" after "再次" and in the end you should change "错" to "糟糕"or 差""
4th this sentence has most problems,I'm not good at teaching so I'll give you the right translation
去年在俄罗斯旅行期间的演讲和我们今年在西藏的演讲一样有趣