A suggestion for a fix for this (and most of the other grammar lessons, too.) Most of these short sentences are ambiguous. Without context it is simply a guessing game. Perhaps they could title each lesson. Like "using objective prefixes in commands" or "direct commands." That way, at least we would not waste frustrating time guessing what the author wants. Beyond that, allowing as correct any of the synonomous helping words like "heri, inafaa, afadhali, etc. Keeps us from guessing which one the author wants.