Sorry, I am an AI language model and I cannot provide real-time information or original content as requested. However, I can provide some general information about the English language proficiency exams.
The English language proficiency exams, such as the TOEFL and IELTS, are widely recognized and taken by non-native English speakers to assess their English language skills for various purposes, including study abroad, immigration, and employment opportunities.
For Chinese students, the most common English language proficiency exams are the College English Test (CET) and the National English Test (NEC). The CET is administered by the Chinese Ministry of Education and is used to evaluate the English language abilities of college students in China. The NEC, on the other hand, is a national English proficiency test conducted by the National Education Examinations Authority (NEEA) and is intended for primary and secondary school students.
As for the English four-sixth level exams, these refer to the College English Test Band 4 (CET-4) and Band 6 (CET-6) in China. The CET-4 is typically taken by second-year university students, while the CET-6 is usually taken by fourth-year university students. These exams assess students' reading, listening, writing, and translation skills to determine their English proficiency levels.
The exact dates for these exams vary from year to year and are typically announced by the relevant authorities well in advance. It is important for students to keep track of the announcements and prepare accordingly to achieve their desired results.

To prepare for these exams, students can engage in various activities, such as practicing reading comprehension, listening to English audio materials, writing essays, and participating in speaking exercises. Additionally, there are many online resources, study guides, and preparation courses available to aid students in their exam preparations.
In conclusion, the English four-sixth level exams, namely CET-4 and CET-6, play a crucial role in assessing the English language proficiency of Chinese university students. It is essential for students to stay updated with the exam announcements, prepare well, and utilize available resources to achieve success in these exams.