题目内容：

课文短文改错

Several Chinese students who they are learning English post their biggest problems on an online forum. Liu Wen used to learning English well, but now he has a lot of trouble on his listening. When listened to native English speakers talking in a video, he can’t get the main idea. Jia Xin thinks listening to English radio programmes help him get used to how fast native speakers talk. He also repeats that he hears. Sometimes he even record his voice but compares his pronunciation with the radio host’s. His most difficult problem is how to polite in English. Li Rui’s biggest problem is vocabulary. She can’t keep all the new vocabulary straight in my mind and she certainly can’t remember how to use them proper.