辐射区 or 辐射污染区

if you prepared a lot of food as dinner for your friend, he/she would say so, meaning we can't eat that much food at one time. Or in other situation, you are preparing food for the following two days but you are not sure whether you have prepared enough, so you asked your friend whether it is enough or not. He/she will say so, meaning that is enough because we will not eat a lot in one meal.

1. 这是我妈妈。 这是我的妈妈。我国家好热。 我的国家好热。Both "的" are optional in spoken Chinese but in written Chinese, the second one should be 我的国家. 2. “必不可少的” is one word "indispensable". That's why "的“ cannot be omitted here. "最有用的" is the same. 3. we don't put "的" after "什么" except “干什么的”（what is it used for? or what do you do?）or "什么做的" （what is it made of?）or "什么味的" （what is the flavor?）...... 4. "我牛角很长" and "我的牛角很长" are both ambiguous because if you say so, i will think you, yourself, are a cow and your horns are long. so it's better to say 我的牛的角很长，which means I have a cow and its horns are long. In one word, normally, if there is no ambiguity, 的 is optional but if 的 is part of a word (like必不可少的，最有用的), it cannot be omitted.

考虑周到。 E.G.他是个很好的旅伴，因为他总是考虑的很周到，把酒店和门票都提前订好。He is a good travelling partner because he always thinks deeply, booking the hotels and tickets in advance.

你想多了！ it is normally used to express the fact that the person was expecting too much (his/her expectation is not going to happen) or 你脑洞太大了！it is used to express the fact that a person's imagination was far beyond the reality (can be neutral or negative)

我是学中文的学生。 上个月我开始学中文，很喜欢，但是很难（this is absolutely fine in spoken Chinese, but in writing, it is better to say 我很喜欢但是我觉得很难 for you to pass exams ）。 汉字很漂亮。 前年我在中国待了两个星期。

明年我还要去中国，所以我在学习中文。

well done! this is a huge achievement since you have learned Chinese for such a short time. just pay attention to the difference between Chinese period and the English one. "回" means you want to go back because you originally lived in China or have lived in China for a long time, so it is not proper to be used here. you can say i will go again ("还要去"). "是故” is a very old way of saying "所以“/”因此". we don't use it quite often now: never in spoken Chinese and seldom in written. Hope your Chinese will be better and better. Thanks.

我的中文没再进步了！

我今年在中国呆了3个月，我在那里的时候，我发现我的中文提高了很多，因为我习惯每天说。我最近4个月住在巴塞罗那，就只有说西班牙语了。然后我再回到这里，我的中文水平就下降了。

well done! it's an understandable article! you must have worked very hard to achieve this! only the last clause is a little bit confusing. according to my understanding, you stayed in China in the past, you have lived in Barcelona in the past 4 months and then you came back to China, realizing your Chinese level was lower. is it correct? if so, "这里" in the last clause in your writing is confusing, because according to grammar, 这里should refer to Barcelona but I think you mean China or italki. If you mean China, you use "回到"这里， which means you came back to China. If you mean italki, you should say 然后我在italki发现我的中文水平下降了。Thanks.

in some context, they are interchangeable while in other context, they are not."waiguo" means "foreign country/countries", whereas "guowai" means "outside your home country". "waiguo" is normally used as adjective, like waiguoren (foreigner) ore waiguohuo (foreign products). "guo wai" is a prepositional phrase, following verbs, like i live in guowai; i went guowai. e.g. i live in "waiguo", emphasizing it is a foreign country that you're living in, while i live in "guowai", emphasize the fact that you are not living in your home country, but "i live in "guowai" is used more commonly. when you refere to the people, foreigners, you can only say "waiguoren". we don't say "guowairen". in most circumstances, they are interchangeable and can be understood well.