短文改错/Proofreading and error correction

It was the chance of a lifetime to win the first prize on the Story Writing Show. All I had to do was to write a story or present it. My teachers have been telling me how great my writing was. So if they had said was true, I would have a chance of winning the prize. What were better, I had useful help. There was Uncle Chen, gentleman living near my house, who was a very much famous writer. He agreed to reading my story and give me some advices on how to write like a real writer.

4（）

下列哪项不属于粗制硫酸铝的特点（）。

A.制造工艺简单

B.含纯硫酸铝20%~25%

C.腐蚀性高

D.比精制硫酸铝便宜20%