题目

判断下列方程组是否为二元一次方程组，并说明理由．⑴ ⑵ ⑶ ⑷ ⑸ ． 答案：解：（2）、（5）中含有2个未知数，并且未知数的项最高次数都应是一次的整式方程，该方程组符合二元一次方程组的定义，故它们是二元一次方程组；（1）中含有3个未知数，所以它不是二元一次方程组；（3）该方程组中一个方程的未知数的最高次数是2，所以它不是二元一次方程组；（4）该方程组The Future of EducationDavid Kelly, founder of the Design School Stanford, said, “In the classroom of the future, education will be custom-made for each student. Every child will have a laptop programmed for his or her learning style and speed. At the same time, more students will go out into the community to learn from business owners. And you’ll see more retirees in the schools as teachers.”A New Way to PayTurn your cell phone into a “mobile wallet” and speed through the checkout line. With a smart phone that uses the same technology as “tap and go” cards, you’ll be able to access your financial data fast. You can select a credit or debit card（借记卡）from the screen, and then tap the phone on the checkout console（操纵台；控制台）.High-Tech GuitarA 26-year-old Australian designer has invented a brand-new way to be a rock star. The Misa Digital Guitar’s fret board looks like a traditional six-string’s but with no strings attached. There’s a touch pad （垫）where the sound hole normally is, and instead of plucking strings,（弹弦） you tap, drag, or brush the pad to “play” the instrument electronically.The Future of PhonesJason Chen, editor of the website gizmodo.com, makes his prediction. “Data connections will get even faster, and you’ll be linked to your environment by cell phone. Fcr example, when you go on vacation, you can point your phone at a monument（纪念碑） and it will give you information about what you’re looking at.’Needle-Free Vaccines（无针接种）Boston University researchers are working on a new method of inoculation（接种）—no injection necessary. A mild electrical charge from a small device, shaped like a gun, is used to drive the particles（粒子） into the body. The new idea beats the old needle method.【小题1】The passage mentions the following EXPECT        .A．paymentB．medicineC．educationD．music instrument【小题2】What can we learn from the text?A．Even a man with no music knowledge can be a rock star in the future.B．Students should go out into the community to learn from business owners instead of staying at school to learn from books.C．We can carry no cash while shopping in the future.D．We can feel more pain with the method of inoculation.【小题3】In which column can we read the passage?A．Entertainment.B．Production.C．Technology. D．Work.