Lily tried to turn the key ___ the lock,but it proved difficult.

题目

Lily tried to turn the key ___ the lock,but it proved difficult.
A in B into C at D onto
请问这里是固定短语还是什么

答案

turn the key in the lock
转动锁眼中的钥匙
固定搭配
例句：She walked into the bedroom and he heard her turn the key in the lock.
她走进了卧室,然后他听见她在锁子里转动钥匙.