--- I hear a number of workers in the factory ______ out of work.

--- Yes, and the number _______ quite huge.

A．are; is

B．is; are

C．is; is

D．are; are

（）能更为直观地反映地层的变化，但由于采集和不易鉴别等因素，在不能准确确定储集层厚度时，综合分析是最明智的作为。

A、岩屑

B、钻时

C、气测

D、钻井液性能