How it works: Prime Minister's Questions (PMQs)

首相提问环节是如何运行的？

reference ：https://www.futurelearn.com/courses/introduction-uk-parliament/2/steps/145219
I'll translate this article later.
Prime Minister’s Question Time (PMQs) is one of the most well known events of the parliamentary week. For half an hour, each Wednesday, MPs are given the opportunity to put questions directly to the Prime Minister on any subject for which the Government is responsible.

Question Time is, above all, a political exchange; it is not about seeking information, which is what written questions are for. Oral questions are about exposing and criticising, or helping and supporting.
How Parliament works, 7th edition p.281 Robert Rogers and Rhodri Walters

The Prime Minister answers questions in the House of Commons each sitting week and, as with most parliamentary business, it is broadcast live. These exchanges are often lively and are regularly featured in the news headlines and shared widely on social media.

Who gets to ask a question during PMQs?

MPs who table (submit) a question enter a ballot for the opportunity to ask the Prime Minister their question during the session. 15 questions are selected at random through a process called the ‘shuffle’.

By convention, the Leader of the Opposition is automatically allowed to ask up to six questions during PMQs. The leader of the second largest opposition party will normally also be called to ask a question.

In addition to this, the Speaker will try to ensure that some political and regional balance is achieved and that a diversity of viewpoints is heard by calling several other MPs to ask a question during the session.

What happens during the session?

The session normally begins with a routine question from an MP about the Prime Minister’s engagements, to which the Prime Minister will respond outlining their upcoming meetings. Due to the high profile nature of the session, the Prime Minister may take the opportunity at this point to make a statement of government policy or to give an official reaction to a recent event. The MP who asked the initial question can then ask a follow-up (supplementary) question, on any subject within the Government’s responsibilities, which the Prime Minister has no prior sight of.

In fact, most MPs choose to table the same ‘engagements’ question so that, when they are called, they simply ask their follow-up question.

This means that the Prime Minister does not know in advance what questions will be asked of them. They will, however, be extensively briefed by government officials in anticipation of likely subjects they could be asked about.

The Leader of the Opposition is usually called early on in the proceedings and, unlike other MPs, has the chance to come back with several further questions. Media attention will often focus on the performance of the two party leaders during these very public exchanges.

Unasked questions

In the past it was common for a session of PMQs to end before all the questions on the Order Paper had been answered. However, the current Speaker, John Bercow, has in his own words,