懂的进,要完整解答+正确率=积分给~

懂的进,要完整解答+正确率=积分给~
1、已知x、y是有理数,且 | 3x – 4 | + (3y + 7 )² = 0,求：
(1) x² + y² (2) x²– 2xy + y²
2、某校六（1）班在春游分组时,同学们作这样安排各中队长任春游小组长,每人负责7名同学.,这样有一组人数不足,若每组减少一人则多余3人,已知六（1）班人数在30～50之间,问该班总人数可能是多少?
3、棱长分别为3厘米,5厘米,4厘米的两个长方体拼凑成一个长方体,它们的表面积最多减少多少平方厘米?
4、已知长方体的长,宽,高之比是5：4：3,用一根长为240厘米的铁丝,制作这个长方体的模型,求此长方体的表面积.
5、一个角的补角与它的余角之比为3∶1,求这个角的度数.
6、线段AB=54cm,C是AB的中点,D是AC上的一点,且CD=2AD,E是BC的中点,求线段DE的长.
( )1.A lot of land becomes deserts because many trees are ____ by people.
A.cut off B.cut in C.cut back D.cut down
( )2.The police are trying to ____ the real murderer.
A.see B.look C.find out D.watch
( )3.The company promises to ____ a meal for each worker.
A.bring B.Provide C.have D.take
( )4.— ____ can we save water?
— By turning off a running tap.
A.When B.Why C.Where D.How
( )5.— How are you feeling today?— ____.
A.I don’t like it B.Thank you
C.Not too bad,thanks D.I’m sorry to hear that
( )6.Let’s the menu first.
A.have a look B.look C.have a look at D.see
( )7.There are many things in the supermarket.will you go to first?
A.Where B.Which section C.What D.When
( )8.Mr Smith has ____ 8-year-old daughter who is very lovely.
A.a B.an C.the D./
( )9.Mr White has more money than Mr Black.But he doesn’t enjoy ____.
A.himself B.him C.his D.he
( )10.Kitty won first prize in the English contest.Her parents are proud ____ her.
A.from B.of C.at D.to
完形填空
The earth is our home.We must take good care of it.That is to say we must (1)k_________ the land,air and water clean.
But man began to (2)p__________ the earth when he first made a fire,washed his clothes in the river and threw dirty things onto the ground.Many years ago,pollution was not so serious(严重的) because there were not so many (3)p__________.There was enough clean air,land and water.When the land or the river was dirty in one place,man moved to (4)a___________ place.But now man is slowly polluting the whole world and there is (5)n__________ enough clean air nor clean land.The more people in one place,the more (6)p____________ there will be.
When is this all to end?Is it possible to get rid of(消除) pollution?We are (7)g____________ to say that people have come to know the danger of pollution and a large number of them are working hard to protect our earth.
英语选择题不要ABCD乱写~

数学题
1.依题意,3x-4=0,3y+7=0,则x=4/3,y=-7/3,则x^2+y^2=65/9,x^2-2xy+y^2=(x-y)^2=(4/3+7/3)^2=121/9
2.可能是31,38,45.设一共分成x个小组,则全班一共有7x+3个,得到30