second-string

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌsecond-ˈstring adjective [only before noun]  UNIMPORTANTnot regularly part of a team, group etc, but sometimes taking someone else’s place in it 〔队、组等成员〕替补的，二线的 the Vikings’ second-string quarterback 北欧海盗队的替补四分卫

Examples from the Corpus

second-string• She watches her lead the second-string players as they widen the margin of victory to thirty-nine points.

ˌsecond-ˈstring adjectiveChineseSyllable  

regularly of Corpus team, group part a not

second-string
ˌsecond-ˈstring adjective [only before noun]
not regularly part of a team, group etc, but sometimes taking someone else’s place in it:
    the Vikings’ second-string quarterback

second-stringBrE /ˌsekənd ˈstrɪŋ/ 🔊NAmE /ˌsekənd ˈstrɪŋ/ 🔊 adjective [only before noun] (especially NAmE) (usually of a player in a sports team 通常指运动队队员) only used occasionally where sb/sth else is not available 替补的◆a second-string quarterback替补四分卫▸ second string BrE /ˌsekənd ˈstrɪŋ/ 🔊NAmE /ˌsekənd ˈstrɪŋ/ 🔊 noun◆Wilson was a second string for New Zealand in last week's match. 在上周的比赛中，威尔逊是新西兰队的替补队员。🔊🔊