题目内容

【题目】听下面一段对话,完成五道小题,每小题填写一个这段对话你将听两遍。

【答案】

(1) 95

(2) 4

(3) Master's

(4) 30

(5) 62 to 72

【解析】听力原文:

There are four basic types of college degrees in America, starting with the associate degree. The associate takes about two years to complete when one is enrolled full-time. The bachelor's degree takes four years of full-time study with the master's taking one to two years, and the doctor's three to four years. The associate degree may be substituted for the first two years of a bachelor's degree if it is a transfer degree. Not all associate degrees are designed for a transfer. Some are technical degrees called terminal degrees, which means they do not count toward a bachelor's. The bachelor's is normally required before one can work at the master's level. Likewise, the master's is normally required before one can work at the doctor's level.

The length in credit hours of university degree programs varies from one school to another. In general, the AA is 60 semester hours or 95 quarter hours. The BA (or BS) is 15 semester hours or 35 quarter hours. The MA is 30 semester hours or 45 quarter hours, and the Ph. D. is 60 to 72 semester hours or 95 to 105 quarter hours.

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相关题目

【题目】雯雯在自学碳酸钠性质时,查到了以下资料:

CO2+Na2CO3+H2O===2NaHCO3,CO2通入饱和碳酸钠溶液会产生白色沉淀,CO2不溶于饱和碳酸氢钠溶液。

碳酸钠、碳酸氢钠在不同温度下的溶解度如表:

0

10

20

30

Na2CO3

7.1

12.2

21.8

39.7

NaHCO3

6.9

8.1

9.6

11.1

【进行实验1】验证CO2通入饱和碳酸钠溶液会产生白色沉淀

配制碳酸钠溶液:取100 g 20 的水,加入35 g碳酸钠固体,搅拌后,静置,取上层清液。

利用装置一进行实验,连续5分钟向新制得的碳酸钠溶液中通入CO2

【发现问题】实验中,始终没有看到沉淀现象,原因是什么呢?雯雯进行了以下实验探究。

【进行实验2】

实验操作

实验现象

取100 g 20 的水,加入35 g碳酸钠固体,搅拌后,静置,取上层清液

利用装置二进行实验,连续5分钟向新制得的碳酸钠溶液中通入CO2

没有出现白色沉淀

(1)在0 ~30 ,Na2CO3和NaHCO3的溶解度受温度变化影响较大的是

(2)大理石与稀盐酸反应的化学方程式为

(3)装置二中饱和碳酸氢钠溶液的作用是

【进行实验3】

实验操作

实验现象

取100 g热开水,加入35 g碳酸钠固体,完全溶解,再降温至20 ,取上层清液

利用装置一和装置二分别进行实验,连续3分钟向新制得的碳酸钠溶液中通入CO2

装置一和装置二中的碳酸钠溶液中均出现白色沉淀

(4)雯雯在最初的实验中没有看到沉淀现象的原因是

(5)CO2通入饱和碳酸钠溶液会产生白色沉淀的原因是

(6)请你依据题中信息,写出一种能够区分碳酸钠和碳酸氢钠固体的实验方案

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