The busier I am, the happier I feel/am.

Nah, >>> the busier i have been,the happier i felt <<< This sounds quite odd.

We separate the two events because one is the cause and the other is the result. Often with "if". "If I had wings then I could fly; I know where I would go." Flying is a result of having wings. Sometimes the cause is in the present and the result is in the future. "I am working now so that I will have some money when I'm old." Sometimes the cause is in the past and the result is in the present. "I bought a camera, now I can take pictures." Often we use this cause and result structure in conditional situations that are unreal. Me having wings for example. This grammar is advanced levels. Regarding adjectives now in cause and result situations. The structure is: "the more (someone) + verb (can be past, present, or future) for the big adjectives and "the _______er (someone) + verb. The cause is before, the result is always after. "The more I read, the more confused I became" The more whiskey he drank, the drunker he got." Here is a famous idiom: "the more the merrier". Use more + two part words, use _______er for little words with only one part. Good Q!

The more xxx,the xxxer.一般的格式是这样。当那个比较的东西没有特殊的方式，如：bad变 worse 一般加-er ，如果连这个也没有就用more xxx表比较。 关于那个句子，你可以用:the busier i have been,the happier i felt(其实第一个答案者那个很不错，为免抄袭，我用了现在完成时和过去时)