at call的用法和樣例：
例句
- The doctors in our hospital are at call day and night.
我們醫院的醫生隨叫隨到。 - He has a large number of reference books at his disposal.
他有大量的參考書可供使用。 - Airliners in service at present cannot fly faster than the speed of sound.
目前供使用的客運機飛行速度不能超過音速。
詞匯搭配
- at the beck and call of 聽候…的吩咐...
- money at call 短期放款
- call at 短暫訪問（某地）...
- at someone's beck and call 唯某人之命是從...
