Customer Feedback Question:

limiting yourself to three types of questions: binaries (yes-or-no questions), scales (asking clients to rate something from 1-10), and open-ended (succinct explanations for client satisfaction or disappointment).
The ideal two-question survey should consist of a first question that is either a rapid-fire binary or scale query, and a second, open-ended question in which you ask clients to (briefly) elaborate on their answer to the first one. But of course, there's nothing preventing you from pairing a binary with a scale, if what you want most of all are quick, quantifiable replies.