1. The subject of "有两层" is also "学校"，it's more Chinese to put those descriptions together without "it", that makes the phrase more simple and clear. 我们学校不新，但（它）很大，（它）离家不远，（它）有两层。 2. An action (verb) finished should be added with 了。 3. Same with the 2. 4. If you want to say "prepare for an exam", you can say 正在准备 or 正在为...做准备。Or, “准备参加...”。Different with the habit usage of English, we use un verb after 准备。If we say 准备+sth, that will mean "have sth ready" ; 准备+verb, eg, 准备考试， means "think about doing""think of, have an idea of, decided taking an exam". 准备+V+O, means "prepare to do sth". "HSK考试" is obviously a proper noun, so there miss a verb, 参加。 5. “Sth/ Sb让我觉得为难” means it embarresses me, or it makes me lose idea, feel hard to make any decision. So I think you actually wanted to say "it makes me feel hard", which in Chinese is "让我觉得很难" or more accented, "这个考试让我觉得特别难". 句子总体来说造得很好！加油⛽