关于从句的问题

suffisait

今天在做OG11黄皮的时候，发现几道从句的问题让我搞不清楚，希望高手可以指点下

1.638面的第五题，As its sales of computer products have surpassed those of measuring instruments,the company has become increasingly willing to compete for the mass market sales it would in the past have conceded to its rivals. 请问为什么划线部分不要加THAT哪？

2.题目：第七题。请问THAT修饰限定性定语从句，WHICH修饰非限定性定语从句怎么理解？不是很明白，限制与非限制是不是一个没逗号，一个有逗号？而且记得原来有听过这2个可以互换的啊？

3.题目P640的第19题。理解有问题：In virtually all types of tissues in every animal species,dioxin induces the production of enzymes that are the organism's attempt to metabolize,or render harmless,the chemical irritant.请问划线部分是什么，宾语还是宾补？有个THE在HARMLESS后面感觉怪怪的。

Looking forward to any reply!!