red/green: wrong/ correction 

yellow [alternatives]: strongly recommended removals and its [alternatives]

blue: strongly recommended add-on

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中国最著名的动物是大熊猫。 但是牠们的数字量真的很少。 牠们最著名的特色是喜欢吃竹子。
大熊猫也是非常害羞 -- 如果人或城市离大熊猫不远[太近]，大熊猫就是会非常不舒服了。

[if I were you]

中国拥有丰富的动物生态环境，和世界上大多数的国家一样，物种涵盖两栖类、爬行类、草食及肉食动物、鸟类...等等。

然而，中国的森林却经常遭受破坏和过度砍伐，随之而来的，是北方沙漠的持续扩张。

熊猫是中国最著名的动物，特色是喜欢吃竹子，但是它们数量很少。熊猫生性害羞，如果栖地与人群或城市太近，熊猫会非常不自在。

中国最著名的动物 - 大熊猫

The read part means that your phrases are grammatically correct and not misleading, but as a native speaker, I think it will be better if you write in this way. 红色的部分是说你的句子语法上没有错而且不会引起歧义，但是作为一个母语使用者，我觉得以这种方式来写会更好。


中国有很多动物的环境。 中国有很多动物的栖息地/适合动物生存的环境。（what you want to say is that China has many places for many animals, right?） 好就像大部分国家的环境一样，中国包含两栖动物、爬行动物、食草动物、食肉动物、鸟类、等等。在中国，动物的种类包括两栖动物、爬行动物、食草动物、食肉动物、鸟类、等等。

但是中国的森林地区总是受难。中国森林总是遭到木材彩云。 但是中国的森林总是遭受灾难，它们总是被砍伐（There is no such expression in Chinese, "木材彩云"。 I think what you wanted to say is "deforestation" right?）而且，中国北方的沙漠一直都是伸展Actually, I don't quite understand this phrase.... 

中国最著名的动物是大熊猫。大熊猫是中国最有名的动物。 但是牠们的数字真的少。但是它们的数量真少。"They" for animals or things without lives, is "它" not "牠", and "数量" is about the amount, but "数字" is number just like"one, two, three.." You can understand this by its key word "字"  牠它们最著名的特色是喜欢吃竹子。
大熊猫也是非常害羞In Chinese, "是" is not used before adjectives, not like in English.For example,"她真漂亮！" We don't say "她是真漂亮！" -- 如果人或城市离大熊猫不远，大熊猫就是会非常不舒服了。

Your Chinese is good, but pay attention to some details, which is often ignored. I suggest that you read some original Chinese articles, that's to say, some articles written by native speakers and observe and contemplate the usage of nouns, verbs and adjectives.

By the way, could you please point out the mistakes that I 've made in English? Thank you very much!

中国最著名的动物 - 大熊猫

中国最著名的动物 - 大熊猫