下列所给出的函数中,是幂函数的是[ ]
A.y=-x3
B.y=x-3
C.y=2x3
D.y=x3-1
答案:B
After 5 days of fantastic space trip ,the two astronauts walked out of the spaceship, ______.
A.tired and happy
B.tired but happy
C.tiredly and happily
D.tiredly but happily
餐饮经济学是()的分支学科,是其在餐饮业这个特定领域的具体化和深化。