单项选择题
A．seeing at night B．seeing objects far away C．looking over a wide area D．judging distances
A．only when we cannot see perfectly B．only when we can see well C．even if we can see well D．only when we realize how important our eyes are
A．the trade of farm birds B．the waste and liquids of infected birds C．the fact that sortie people touched sick birds or any infected part of sick birds D．the virus changed and started spreading in some new forms