Lightning has been the second largest storm killer in the US over the past 40 years and is （）only by flood.

单项选择题We have no figures on the number of workers employed in the （）stages of iron production.

A. various
B. variable
C. varied
D. variant

单项选择题The president of the company （）why the other members of the committee hadn't been informed of this important news.

A. required
B. acquired
C. inquired
D. requested