如下 when引导的什么从句that呢

问题描述:

如下 when引导的什么从句that呢
Imagine their surprise and delight when they broke open the packing cases and found that the fourth engine was sweet as honey -- still in perfect condition. when引导的什么从句that呢

此句中when引导的是时间状语从句,that 引导的是宾语从句.