A．We are better than others．
B．We are good enough to succeed．
C．We deserve all the goodness．
D．We could be a better self．

A．Age．
B．Sex．
C．Nutrition．
D．Income．

A．Because they are busy with their career in this period．
B．Because they aren't conscious of health．
C．Because people of this age belong to the most cold-ridden group．
D．Because having children makes them easy to be infected．