随着收入水平的提高，李达凯打算卖旧房买新房，旧房值100万元，_爱下问搜题

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问题单项选择题

随着收入水平的提高，李达凯打算卖旧房买新房，旧房值100万元，贷款尚有60万元，新房值150万元，拟贷款80万元，现在李达凯手中有市值15万元的股票可抛售用于首付，则李达凯需另筹首付款（）万元。

A.10

B.15

C.20

D.25

答案

参考答案：B

解析：

需筹首付款=新房净值-旧房净值=(新房总价-新房贷款)-(旧房总价-旧房贷款)=(150-80)-(100-60)=30(万元)；需另筹首付款=需筹首付款总额-股票=30-15=15(万元)。

阅读理解

阅读理解。

A Simple Scientific Experiment

Below is a description of a single scientific experiment . It shows us how iron reacts ( 反应) with air and
with water.
Aim : To find out if iron rusts( 生锈) (a) in dry air ; (b) in water that has no air in it ( air- free water) ; (c)
in ordinary water.
Materials : 3 clean iron nails ( 铁钉) ; test tubes ; test tube holder ; cotton wool ; oil ; Bunsen burner.

Iron in dry air
Method
(1)Put some iron nails at the bottom of a test tube.
(2)Push some cotton wool down the tube.
(3)Leave the tube for one week.
Result
After one week, the nails have not rusted.
Conclusion
Iron does not rust in dry air.
Iron in air-free water
Method
(1)Half-fill a test tube with water.
(2)Boil the water for three minutes.( This makes sure
there is no air in the water.
Put two or three clean nails in the water.

(4)Add some oil to the water. ( This will keep
air out of the water.)
(5) Leave the tube for one week.
Result
The nails do not rust in the tube with air-free
water.
Conclusion
Iron does not rust in air- free water.
Iron in ordinary water
Method
(1)Half -fill a test tube with water and add two
or three clean nails.
(2)Leave the tube for one week.
Result
The nails rust in the tube with ordinary water.
Conclusion
Iron rusts in ordinary water.

1. In the first part of the experiment the cotton wool is most probably used to ______________.
A. dry air
B. cotton wool
C. ordinary water
D. air-free water

2. What are necessary steps to make sure the water in the tube is air free?

①Leave half a tube of water in it                ②Boil the water for some time
③Put some clean iron nails in the tube        ④Add some oil to the water
  A. ①②                  B. ①③                 C. ②③                D. ②④

3. We can conclude from the experiment that only ____________ makes iron rusty.

A. keep the air dry
B. keep the tube wet
C. make the nails rust
D. keep the tube clean

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