Since letter grades were introduced several months ago, we’ve seen them used every which way. Cer Te used its “B” to spell out “BEST,”; d.b.a. turned its “B” into a name tag; restaurants have given themselves fake “A”s; and even bookstores and liquor stores have gotten in on the action. But this one’s new: A letter grade on a take-out menu! When you find this on your stoop, you can rest assured your local Chinese joint is squeaky-clean, even if it likes to litter.