求英语高手帮忙分析下面的句子,black substance made from coal tar,turpentine or petroleum which is sticky and semi-liquid when hot,and hard when cold,and is used to fill in cracks or spaces,eg between the planks of a floor or of a ship"s

Question

求英语高手帮忙分析下面的句子,
black substance made from coal tar,turpentine or petroleum which is sticky and
semi-liquid when hot,and hard when cold,and is used to fill in cracks or
spaces,eg between the planks of a floor or of a ship's deck,to make roofs
waterproof,etc .
句中的 when hot 和 when cold 这样的用法感觉好奇怪。另外，望高手帮忙划分出句子成分。

Answer 1

黑色物质由煤焦油、松节油或石油,粘粘的,当热的时候,硬的时候冷,是用来填补裂缝或空间,如木板之间的一层或一艘船的甲板,使屋顶防水等.
应该是when加形容词表‘当什么的时候’