Millions of people watched that first moon landing on television their hearts in their mo

问题补充：

Millions of people watched that first moon landing on television, their hearts in their mouths, aware of how difficult and dangerous an adventure it was, and what risks had to be .

A. taken

B. take

C. to take

D. taking

答案：

(答案→)A. taken

B. take

C. to take

D. taking

解析：考查非谓语动词。短语：take risks冒险句意：成千上万的人在电视上观看了第一次在月球上着陆，他们的心衔在嗓子眼，意识到了是一次多么困难危险的经理呀，不得不冒险。根据语境选A。