根据有关规定企业签发的商业汇票的最长期限为（）
A．3个月
B．6个月
C．9个月
D．一年
参考答案：B
请用英语写出奥运五环旗的五种颜色。
1._____2._____3._____4._____5._____
The old .engineer’s eyes still shone bright in the wrinkled brown face and his step as he came across the room was________，though slow.
A．shaky
B．heavy
C．casual
D．steady
