sign in phrasal verbphr v a) SIGN YOUR NAMEto write your name on a form, in a book etc when you enter a place such as a hotel, office, or club 签到 Remember to sign in at reception. 别忘了在接待处签到。
b) sign somebody ↔ inDLSIGN YOUR NAME to write someone else’s name in a book so that they are allowed to enter a club, an office etc 为〔某人〕登记〔使其得以进入俱乐部、办公室等〕
→ sign in at sign2(PHRASAL VERB)