BGO是我国研制的一种闪烁的晶体材料，曾用于诺贝尔奖获得者丁肇中的著名实验．BGO是锗酸铋（化学式为Bi4Ge3O12）的简称．已知在BGO中锗（Ge）的化合价与GeO2中锗的化合价相等，则在BGO中铋（Bi）的化合价为（ ）
A．+2
B．+3
C．+4
D．+5
在GeO2中，O元素的化合价为-2价，设Ge元素的化合价为x，
由氧化物的化学式和化合物中正负化合价的代数和为0，则
x+（-2）×2=0
解得x=+4，即Ge元素的化合价为+4价；
在Bi4Ge3O12中，Ge元素的化合价为+4价，O元素的化合价为-2价，
设该化合物中Bi元素的化合价为y，
由化学式和化合物中正负化合价的代数和为0，则
y×4+（+4）×3+（-2）×12=0
解得y=+3
故选B．
(2013·高考江苏卷)I used to believe in the American Dream，which meant a job，a mortgage (按揭)，credit cards，success.I wanted it and worked toward it like everyone else，all of us ____ chasing the same thing. One year，through a series of unhappy events，it all fell ____.I found myself homeless and alone.I had my truck and $56.I ____ the countryside for some place I could rent for the ____ possible amount.I came upon a shabby house four miles up a winding mountain road ____ the Potomac River in West Virginia.It was ____，full of broken glass and rubbish.I found the owner，rented it，and ____ a corner to camp in. The locals knew nothing about me，____ slowly，they started teaching me the ____ of being a neighbor.They dropped off blankets，candles，and tools，and began ____ around to chat.They started to teach me a belief in a ___ American Dream—not the one of individual achievement but of ___. What I had believed in，all those things I thought were ____ for a civilized life，were nonexistent in this place.____ on the mountain，my most valuable possessions were my ____ with my neighbors. Four years later，I moved back into ____.I saw many people were having a really hard time，___ their jobs and homes.I managed to rent a big enough house to ____ a handful of people.There are four of us now in the house，but over time I’ve had nine people come in and move on to other places.We’d all be in ____ if we hadn’t banded together. The American Dream I believe in now is a shared one.It’s not so much about what I can get for myself; it’s about ____ we can all get by together.
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