1. Heard
2 is correct
3. Said
4. Sold
5. Go
"Work ethos" is a compound expression built on the greek word "ethos" (referring to an idea of "habit" that often is ascribed to one's personal/moral tendencies).
With the adjective "work" preceding ethos, the expression refers to a person's work ethic (we can see how "ethic" comes from "ethos" visually in the spelling, too).
"Work ethos" is best understood by the more common (and synonymous) expression, "work ethic."
Answer:
A. A business letter provides a record of the contact with all of the details.
The verb here is "had given"; this is past perfect: it's a perfect tense, because it has a past participle with the -ed ending ("given") and it's the past perfect because the auxiliary verb is the past form of "have": had.
