托福的听力对于很多的考生来说，也是一个难题吧，大家在快要考试的时候，看一看机经预测对于自己是有很大的帮助的，下面和出国留学网小编一起来看看2018年5月12日托福考试听力预测。
题目：
1. What is the main purpose of the lecture？
A. To discuss the advantages of heating substances in microwave ovens
B. To discuss recent research that may lead to improved microwave ovens
C. To point out problems in the use of superheating to produce medicines
D. To prepare students for upcoming experiments in the laboratory
2. Why does the professor talk about making coffee？
A. To describe how he dissolved coffee particles to prevent nucleation
B. To introduce the concept of microwave superheating
C. To reassure the students that some of the experiments will be as simple as making coffee
D. To warn the students not to superheat liquids containing dissolved chemicals
3. Why does the professor mention that once nucleation has occurred， added heat is used to convert liquid water into water vapor？
A. To explain why the temperature of water does not rise beyond the boiling point when water is heated in a metal pot on a stove
B. To point out similarities in heating liquids using microwave ovens and using conventional stoves
C. To explain why water that is exposed to microwaves will appear to be hot when it really is not
D. To point out that it is better to avoid making coffee in a microwave oven
4. The professor talks about using microwave ovens for superheating during the students＇ laboratory experiments. What two possible results of superheating does he mention？
Click on 2 answers.
A. An increased flow of electrical current through the superheated liquid
B. An acceleration of reaction between chemicals in the superheated liquid
C. The decomposition of chemicals in the superheated liquid
D. The creation of tiny scratches and dents on the interior surface of the container
5. What is the professor＇s attitude about the use of microwave ovens by pharmaceutical companies in the production of medicines？
A. The use of microwave ovens is hazardous because it prevents control of temperatures.
B. The use of microwave ovens produces satisfactory results but is not worth the added expense.
C. The use of microwave ovens may allow companies to produce medicines more efficiently than traditional heating methods do.
D. More research should be done before replacing traditional heating equipment with microwave ovens.
6. According to the professor， what two laboratory practices that are used by pharmaceutical companies will students also use in their experiments？
Click on 2 answers.
A. Using containers that have been developed to ensure nucleation
B. Using a new type of microwave to superheat all liquids
C. Using smooth containers that have been specially designed for microwave use
D. Using sealed containers to allow the pressure inside to increase during heating
答案：1-6
D、B、A、BC、C、CD
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