题干
- Are you going to the bank, Laura?
- No, I _______ to the bank already.
- No, I _______ to the bank already.
A：have been
B：have gone
C：am going
D：had been
答案(点此获取答案解析）
A
。为使弹簧振子的振幅最大,则电动机的转速应为( )
在点（0,2）处的切线与直线y=0和y=x围成的三角形的面积为