Not difficult. English for medical doctors with the same education is not difficult, because it belongs to entry-level English. Applicants only need to pass CET-3 (PETS5) and CET-4. In addition, if your English level is low, you can improve your English ability by taking part in English courses and academic English speech contests. Generally speaking, it is not difficult for medical doctors with the same academic level to learn English, but they need to prepare in advance to improve their English.