A．Some people don't want to take it because it's too time-consuming．
B．The results might not be objective enough．
C．The survey aims to measure Americans' happiness．
D．The survey has been conducted for three months．

A．The English word "happenstance" is about luck that happens by chance．
B．Happiness means good luck in many languages．
C．Happiness as a kind of feeling is relatively long-lasting．
D．People's feeling of happiness goes back to normal quickly．