序数词“第八”的英文写法是“（）”。
A、eighth
B、eight
C、eighteenth
D、theeight
参考答案：A
The suggestion that is worth _______ is that the students should learn something practical. [ ]
A. being considered
B. to be considered
C. to consider
D. considering
表示光纤色散程度的物理量是（）
A.时延
B.相位差
C.时延差
D.速度差
