It was four o'clock in the afternoon ( ) he and his team reached the top of the mountain.

问题描述:

It was four o'clock in the afternoon ( ) he and his team reached the top of the mountain.
答案是when 不是that 为什么是状语从句 不是强调句 如果把It was 和 that 去掉仍然句子成立

强调句特点是去掉it is 和that 依旧成立
这里
he and his team reached the top of the mountain (at) four o'clock in the afternoon
少一个at不成立,是先行词作状语的定于从句,不是状语从句