听力原文：M: Could you tell me a bit about quality control at the factory? W: Well, there are four main quality control inspection points. We begin by visiting our suppliers to make sure we are happy with their quality control. Next, we inspect all goods on arrival at our factory and the third inspection point is during production. And the last stage is chemical analysis of our finished goods. M: And what do you look for at each of the four inspection points? W: Well each stage is different. With our suppliers, for instance, we inspect their quality control processes and, even more importantly,their factory hygiene. If we're not happy with their hygiene, we'll cancel the supply contract. As the goods is in stage, we make sure that order quantities are correct and the quality is OK. We also check the transport packaging. If the packing is damaged, the warehouse shelf-life can be reduced. M: And what quality checks do you run during production? W: We take samples to check there isn't too much cooking oil on the snack and that each snack has the minimum amount of flavouring. We also check the size of the snacks and their crispness.If the snacks are too oily, they go soft. M: So that leaves the finished goods. What do you check for at the final quality control stage? W: We check individual bags to make sure that the packet weight is above the acceptable minimum and that the packet is sealed properly. We also cheek the taste. M: And how do you do that? W: Well, we eat them. How else? We also do chemical analysis to check things like fat levels and other information that we have to put on the packets. Questions 23-30 ?You will hear a conversation about quality control. ?For each question (23-30), mark one letter (A, B or C) for the correct answer. ?After you have listened once, replay the recording. How many are there quality control inspection points. A．Three B．four C．five