If its message were confined merely to information and that in itself would be difficult if not impossible to achieve, for even a detail such as the choice of the color of a shirt is subtly persuasive----advertising would be so boring that no one would pay any attention.

【翻译】如果广告词仅仅局限于传递信息，假若说这能够做得到，实质上是很难做到的，因为甚至像选择衬衫颜色这样的细节，都要精雕细琢去打动人心；果真那样的话，那广告就会变得无聊之极，没人去理会它了。

【注】红色部分为条件句，蓝色部分为主句。

【分析】

1. 本句使用了虚拟语气。

2. 条件从句：If its message were confined merely to information and that in itself would be difficult if not impossible to achieve, for even a detail such as the choice of the color of a shirt is subtly persuasive

3. 主句：advertising would be so boring that no one would pay any attention.

4. 在条件从句中，its message were confined merely to information 与 that in itself would be difficult if not impossible to achieve 是并列关系，for even a detail such as the choice of the color of a shirt is subtly persuasive 为这个条件从句提供理由，并且与之并列。