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问题 单项选择题

影响沉淀试验的因素包括（）

A.抗原与抗体的比例

B.温度

C.盐浓度

D.以上三项

E.仅B+C

答案

参考答案：D

解析：抗原抗体的比例、溶液的温度及离子强度等均影响抗原抗体反应

阅读理解
Look at this mail-order advertisement:
SUNSHINE COMPANY
Products for a Safe Environment
A2477—l
You're going to love this natural soap.There are no chemicals in it.It is very good for your hands and face.
D4545—GARDEN SPRAY
Insects are going to run away from our new chiligarlic spray.It's safe and natural.
B2377—HOME CLEANERYou're not going to need 5 or 6 chemical cleaners.You have Dr Clean!It is safe and strong,and it cleans everything in your house!
A2104—CANVAS BAG
You're going to say,“No paper or plastic!”You have this excellent heavy canvas shopping bag.

item
code
price
Natural ampoo
T6762
$3.00
garden spray
D4545
$2.50
canvas bag
A2104
$4.00
hand soap
A2477
$1.00
home cleaner
B2377
$2.25
Postage:$3.50
小题1:Dr Clean is _________.
A．an expert in cleaning everythingB．a newly-invented machine
C．a can of cleaning powderD．a magic cloth for cleaning
小题2:According to the ad,where can you mail your letter if you want something to kill the ants?
A．D4545 Garden Spray.B．Sunshine Company.
C．A2104 Canvas Bag.D．The Dr Clean's.
小题3:You're going to love the natural soap,because _________.
A．it is cheapB．it smells sweet
C．there are no chemicalsD．it is powerful
小题4:According to the ad,how much do you have to pay for 3 shampoos and 2 canvas bags totally?
A．＄12.25.B．＄20.50.C．＄13.50.D．＄17.
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选择题

神经系统中有“生命中枢”之称的结构是（　　）

A．大脑

B．脑干

C．小脑

D．脊髓
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