Since the first patent was granted, there have been ________ patents granted in the United States.
A、526,000
B、2.3 million
C、4.6 million
D、9.6 million
E、12.2 million
发布时间:2025-07-18 06:04:10
A、526,000
B、2.3 million
C、4.6 million
D、9.6 million
E、12.2 million