以下是定语从句用which而不用that的情况。
1. 非限制性定语从句的情况下肯定不能用that作引导词。非限制性定语从句由逗号隔开,所以在阅读时如果看到逗号后有that的情况,那么这个that肯定不是用于引导定语从句。
Green tea is rich in anti-oxidants,which gets your blood moving and improves your energy level. 绿茶富含抗氧化剂,能促进血液循环并提升能量水平。
They offered him some money,which he refused politely. 他们要给他一些钱,他婉言拒绝了。
2.限制性定语从句中只能用which而不用that的情况比较少见,但需要注意以下情形。
1) 当定语从句是由“介词 + 关系代词”引导时,其中的关系代词就只能用which而不能用that。
They lost sight of the reasonsfor which they went to war. 他们忽略了他们去打仗的原因。
Humor was a meansby which the American writers would win popular acceptance of their readers. 幽默是美国作家迎合读者的一种手段。
2) 当先行词为 that 或those 时,关系代词只能用which而不用that,以避免重复。
Natural water is thatwhich contains impurities. 天然水是一种含有杂质的水。
Marine creatures are thosewhich live in the sea. 海洋生物是生存在海里的生物。
3) 另外,which 还可以用作限定词,后跟名词,that 则没有这个用法。
I may not be in the office, inwhich case you could leave me a note. 我不一定在办公室 ,如果是那样你可以给我留个便条。
The Shang dynasty, duringwhich period China's written history began, made its capital in Henan. 商朝定都河南,中国有文字记载的历史是从这个时期开始的。