Yesterday ______________ my birthday. [ ]
A. am
B. were
C. was
D. is
答案:C
公众态度
在无差异曲线上,重视闲暇者的无差异曲线( )。
A.较为扁平
B.较为陡峭
C.垂直于横轴
D.垂直于纵轴