The encouraging letter was like a shot in the arm.

这封鼓舞人心的信，宛如一服兴奋剂。

You need a shot in the arm.

你需要在臂上打一针。

The new members gave the club a shot in the arm.

新成员给该俱乐部增添了新鲜血液。

Please take off your coat and I will give a shot in the arm.

请脱下外套，露出手臂，我将帮您注射。

The Queensland floods are giving a shot in the arm to steel prices.

昆士兰洪灾给钢铁价格打了一针强心剂。