题目

计算：（m+n）2﹣（m+n）（m﹣n）+2mn ． 答案：解： (m+n)2−(m+n)(m−n)+2mn =m2+2mn+n2−m2+n2+2mn =2n2+4mn China is running ahead in 5G. Last month, the Shanghai Hongqiao Railway Station _______ the world’s first “5G railway station”. Now it _______ only 20 seconds to download a long movie there.We are moving closer and closer to the 5G world. However, the new technology is still _______ to most of us. What is 5G, after all? The first feature of 5G is obvious — it is _______. 5G will not only be faster than the current 4G networks. It will _______ be much faster than the broadband(宽带) connection we have at home!The first 5G modem(调制解调器) of the IT company Qualcomm supports the _______ of up to 5 gigabytes(千兆字节) per second. Most of us have never experienced _______ close to that speed. And we are only talking about the first generation of 5G modems. Future modems are likely to be even faster._______ 5G is not all about speed. Have you ever been to a large event where your data(数据) connection slowed down? That is _______ 4G networks can only support a certain number of devices(装置、设备) per square kilometer. 5G networks will be able to do much ________. They can support up to a million devices per square kilometer.Now, you begin to ________ why 5G is a huge upgrade over 4G. The technology is not just for the smart phone. It has a strong ________ on every connected device. ________ 5G self-driving cars will be able to communicate with the world around them as quickly as possible. They will be ________ independent. Wearables(可穿戴设备), PCs and smart home appliances will be able to be ________ as well. Are you looking forward to it?1.A.described B.became C.connected D.caused2.A.takes B.spends C.costs D.pays3.A.successful B.harmful C.strange D.good4.A.fast B.slow C.common D.unusual5.A.too B.either C.also D.neither6.A.task B.speed C.weight D.height7.A.anything B.something C.nobody D.anybody8.A.So B.But C.And D.Or9.A.while B.since C.because D.whether10.A.better B.worse C.well D.bad11.A.mention B.understand C.doubt D.prove12.A.chance B.level C.influence D.mind13.A.With B.From C.For D.To14.A.completely B.simply C.mostly D.nearly15.A.discovered B.happened C.improved D.begun