stand-by

n (pl -bys) 1 person or thing available as a substitute or in an emergency 後备人员; 备用的事物: Aspirin is a good stand-by for headaches. 阿司匹林是必备的头痛良药. * [attrib 作定语] a stand-by ticket, ie a cheaper type of airline ticket available when not all the tickets for a flight have been sold 剩余机票（因未事先售出而价廉）. 2 (idm 习语) on `stand-by in a state of readiness 待命状态: The troops are on 24-hour stand-by, ie ready to move within 24 hours of receiving the order. 部队待命24小时（接到命令後24小时内可行动）.

stand, stand (sb) to, stand a chance, stand a good chance, stand back (from sth), stand by, stand down, stand for, stand for sth, stand in (for sb), stand in one's way, stand no chance, stand out, stand out (from/against sth), stand over sb, stand sb up, stand the test, stand up, stand up for, stand up to, stand-in, stand-off half (also `fly-half), stand-offish, stand-offishly, stand-offishness, stand-pipe, stand-up, standard, standard lamp (US `floor lamp), standard of living, standard time, standard-bearer, standardization, standardisation, standardize, standardize, standardise, standing, standing order, standing ovation, standing-room, standpoint,