I'm trying to sort out the difference between 免费 and 无偿 as adverbs. Would you say 水果店的老板免费送了我六个苹果。 or would it be 无偿送了？
我们,咱们 both means: we, but when I should use 咱们， 我们？ What is the difference?
Is it mostly a question of register?
If I understood correctly, both 完 and 了 can be used to indicate a completed action, so what is the difference in use? How do we properly use 完 in a sentence? Which contexts would be valid?