sign on
phrasal verb with sign verb uk/saɪn/ us/saɪn/
(NO JOB)
UK informal（到政府就业事务处）登记领取（失业救济金）
to sign a form at a government office to say that you do not have a job and that you want to receive benefit (= money paid by the government)
(AGREE TO HELP)
mainly US (UK sign up)报名参加（某项有组织的活动）
to agree to become involved in an organized activity
[ + to infinitive ] mainly US I've signed on to help at the school fair. 我已报名在学校交流会上帮忙。
UK informal签约（受雇）；报名（参加活动）
to sign a document saying that you will work for someone or do a particular job or activity
She's signed on with a temp agency. 她和一家临时机构签约了。