It is best not to apply. The CET-4 training class just tells you some problem-solving skills. There are really few things to be tested in CET-4, and the vocabulary requirement is very low.

Usually remember more words, the vocabulary has passed, so it can be said that you can pass Band 4. Then practice listening more often. Listening is different from ordinary reading and writing, just like oral English. Practice more and you will become proficient. Listening is also a good way to score.

In addition, if you usually read more English articles, you can read simple ones, cultivate a sense of language, and don't give up. Whether you pass or not depends not on your previous foundation, but on whether you have really worked hard, and your ability is similar. Have confidence!