地球公转产生地的现象是（　　）

A．形成春夏秋冬四季

B．出现时间差异

C．昼夜更替现象

D．昼夜现象

It seems ________ to our modern world, where everything is a rush and we try to cram as much into every minute as possible, but if not busy, we feel unproductive and lazy.

A．controversial

B．conventional

C．contemporary

D．contradictory