Perhaps economy is the answer
Yes, I think so. Fluent means he knows the language by heart whether that is his first language or not. However, he still could forget some things. Here in the U.S. We still look stuff up all the time in dictionary's or on our phones even though we are fluent in the language. So getting a French dictionary will help more.
A subject-verb agreement error
occurs when the number (whether or not something is singular or plural) of the
subject does not “agree” with the number of the verb. For instance, if a subject is singular, the verb
should be singular as well, and this is known as “agreeing.” If the subject is singular, but the verb is
plural, then this is known as a subject-verb agreement error (or subject-verb
disagreement). Below, the agreement
errors have been corrected to the proper number and appear in bold.
"This new technology is for everyone and will revolutionize the lives of millions of ordinary commuters. Cheaper than concrete or tarmac but just as durable, the new cycling paths absorb light and re-emit it when they sense that it is required. They're one hundred percent environmentally-friendly. The inventor, however, is less forthcoming when our conversation turns to how the product actually works. Despite a barrage of questions, the only thing he will admit to is that the key to this techno-wonder is a combination of recycled tires (what else?) and a specially formulated light-emitting powder that charges during the day and glows at night."
After reading this excerpt it seems to me that the story takes place in <span>a deserted town in which mysterious events occur. Some points of the plot also lead me to this answer, as most of actions and events in this story were represented in an abandoned town with strange ad weird things people may come across if they once come to the town.
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