At present, there are some mobile phone applications and websites dedicated to the practice of theoretical examination of chef's certificate. These resources usually provide a question bank of chef's theoretical knowledge and a mock exam to help candidates get familiar with the exam questions and improve their problem-solving ability.

Here are some possible platforms:

1. Chef Exam official website: Some areas may have official website or application of Chef Certificate Exam, providing a practical question bank for relevant theoretical exams.

2. Website or application of exam training institutions: Some professional exam training institutions may provide online practice question bank and mock exam for the theoretical exam of chef certificate.

3. Online education platform: Some well-known online education platforms may provide relevant question banks for the theoretical examination of chef's certificate, where candidates can find relevant resources.

Before using any application or website to practice, it is recommended to confirm its legitimacy and authority to ensure that the content you have learned meets the requirements of the official examination.