A．Within the first week of class．
B．Two weeks before the final due date．
C．By the end of the term．
D．A week after the last class．
A．Milder weather in recent years．
B．An increase in gasoline prices．
C．Construction of bicycle paths．
D．The invention of sturdy bicycles．
A．Unavailability of warm clothing．
B．Bicycle maintenance．
C．Increased illness．
D．Increased commuting time．