无效

of (or to) no avail; invalid; null and void

♦ 医治~ fail to respond to medical treatment

♦ 宣布合同~ declare a contract invalid (or null and void); invalidate (or nullify) a contract

♦ 宣布选举~ nullify an election

~分蘖 [农]ineffective tillering~劳动 fruitless labour; labour lost