Again, I generally like "Du's Handbook," but, again, I do not like the way it provides translations without explanation. The above sentence, for example, is an example sentence from a section on "Interrogatives," which explains that 乎 (호) is a character that can be added to the end of a statement to turn that statement into a question, essentially asking at the end of the statement if it is true or not. Here is a more literal translation of the sentence.飮而棄酒, 於禮可乎Is it polite to throw away the wine you have been given?
What good does it do to give a translation without explanation? If you are teaching something as simple as the question marker 乎 (호), that is an indication the reader is a beginner, who would probably require a more detailed explanation of the whole sentence. So why doesn't "Du's Handbook" do that?飮而棄酒, 於禮可乎To drink [a little] (飮) and then (而) throw away (棄) the wine (酒), according to (於) etiquette (禮), is permissible (可), right or wrong (乎)?
The following is part of the "Introduction to the Handbook":
The main material for this book was used continuously for close to thirty years by Durham University's Classical Chinese students. Archie Barnes's grammar work has been edited and in places re-worked for the lone student...."Notice that the introduction explains that the book was used as part of a college course, so such books are often written in a way to keep students reliant on a professor for detailed explanation of the translations. In other words, too much explanation may cause students to wonder if they really need a professor. But the above introduction also says that "Du's Handbook" was, "in places re-worked for the lone student." I believe them, but I think they could have "re-worked" it in many more places.
By the way, the small dictionary at the back of "Du's Handbook" defines 於 (어) as meaning "at," "in," "on," "to," "from," "by," "then," "towards," "and," and "moreover," but it forgot to include the meaning "according to," which in Korean is 따르다.