钟形分布的特征是两头大、中间小。（）
参考答案：错
As the years passed, many occasions—birthdays, awards, graduations — __________ with Dad’s flowers.
A．are marked
B．were marked
C．have marked
D．had marked
计算机网络的突出优点是()。
A．速度快
B．资源共享
C．精度高
D．容量大
