输液在英语中的表达是 "infusion". 这个词来源于拉丁语 "infusio"，意思是 "浸泡"或者"灌入"。

例句：

The doctor ordered an infusion of saline solution to hydrate the patient.

(医生给病人输入盐水解决方案来保持水分。)

The nurse carefully monitored the infusion to ensure the correct dosage.

(护士仔细监控输液，以确保正确的剂量。)

The patient's condition improved significantly after the infusion.

(病人在输液后状态明显好转。)