Every school admits that the core is different. It is useless to send a strong core after the initial test. Generally, you can go after the second interview online. Some majors are difficult to send the core. If you don't hang the fund project, the editor will refuse it without reading it. The review period is also very long. It takes a year to a year and a half from the initial record. What can be sent in a month or two is definitely not the core. Ordinary undergraduates should not consider this aspect.