--Why does the Lake smell terrible?
--Because large quantities of water .
A． have polluted B. is being polluted C. has been polluted D. have been polluted

A.1
B.2
C.3
D.4

A.奇函数，且在（0，+∞）单调递增
B.偶函数，且在（0，+∞）单调递减
C.奇函数，且在（-∞，0）单调递减
D.偶函数，且在（-∞，0）单调递增

A.艰苦奋斗防腐拒贿
B.艰苦奋斗甘当公仆
C.甘当公仆防腐拒贿
D.甘当公仆清正廉明