it was about 600 years ago___the first clock with a face and an hour was made Awhen B that,前面先行词不是时间吗,我觉得应该用when,但答案是that,这取决与什么啊,后面的动词吗,常常分不清,具体说一下好吗,还有前面是地点,什么时侯用where和that,举例说明

it was about 600 years ago___the first clock with a face and an hour was made Awhen B that,
前面先行词不是时间吗,我觉得应该用when,但答案是that,这取决与什么啊,后面的动词吗,常常分不清,具体说一下好吗,还有前面是地点,什么时侯用where和that,举例说明