作證

to bear witness; to testify / to serve as evidence

worker / workshop / (slang) troublesome / high-maintenance (person)

to do; to engage in / to write; to compose / to pretend; to feign / to regard as; to consider to be / to be; to act the part of / to feel (itchy, nauseous etc) / writings; works

certificate / proof / to prove / to demonstrate / to confirm / variant of 症[zheng4]

competence