Locate the participle (not the entire participial phrase) and the word it modifies.

"riding on the bus, we watched the landscape float by."

participle:
modified:

He united states can produce 200 pillows in one week, while spain and france produce 150 and 100 pillows, respectively, in one week. on the other hand, spain can produce 10 televisions in one week, while the united states and france produce only 5 and 4 televisions, respectively. has an absolute advantage in producing pillows, and has an absolute advantage in producing televisions.