Our special thanks to go thousands of volunteers, without tireless work, none of this would be possible.
A. which
B. whom
C. whose
D. that
网友回答
A. which
B. whom
(答案→)C. whose
D. that
解析：句意：我们特别感谢成千上万的志愿者，没有他们不辞辛苦的工作，这一切都不会成为可能。without tireless work是非限制性定语从句，修饰volunteers，所填词要做定语，用whose 。所以选C。