密度知识与人们的社会生活关系十分密切，以下说法正确的是（　　）

材料一：中国青年报关于微信群讲座的问卷调查

材料二：李婧怡介绍，组织一场微信群讲座需要做很多准备。“首先要确定主题，做策划，邀请嘉宾，根据嘉宾需求调整策划，微信发推送做预热，邀请粉丝入群。沙龙进行时会先介绍主题、嘉宾、规则，然后是嘉宾互动环节，再是自由提问环节。结束后会把整理的沙龙内容发给群内读者，未来相关内容也会发到群里，与读者互动”。

互联网“微商”经营已成为大众创业新途径，某微信平台上一件商品标价为200元，按标价的五折销售，仍可获利20元，则这件商品的进价为（　　）

                                                                                               House of Porridge
    Welcome to Clark's Porridge House. We have different kinds of porridge. We have meat porridge, vegetable porridge. And fruit porridge is our special, it is only RMB 4 yuan for one bowl. A bowl of meat is RMB 5 yuan. Vegetable porridge is RMB 3 yuan for one bowl, but RMB 5 yuan for two. We have thin pancakes, too. They are RMB 5 yuan for ten. Come and taste the delicious food here. If you are too busy to come, make a telephone call to us and we can send the food to you in 20 minutes.
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