数字式探测器具有限宽的探测范围，当检测的（）规格发生变化时也无需重新调整探测器的位置。
A.硬度
B.带钢宽度
C.长度
D.波浪程度
参考答案：B
The farmers needed________agricultural technology. Therefore, ________skilled workers were sent there.
A．a great number of, a large amount of
B．large amounts of, the number of
C．a large amount of, a great number of
D．the amount of, a great number of
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