[转载]Core Elements of a Program

原文链接 http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00sc-introduction-to-computer-science-and-programming-spring-2011/unit-1/lecture-2-core-elements-of-a-program/

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what is a "type"?

　　Types are classifications of objects, which is what Python, as an OOP language, deals with. They determine how those objects are dealt with (for example, adding two intergers resultes in an interger, two strings results in a concatenated string, and an interger and a string results in an error).

What is an 'expression'?

　　An expression is composed of objects (or operands[n. the number on which an operation is to be done 操作数]) and operators, and can be interpreted into a value.

What is a type conversion? [类型转换]

　　A type conversion turns one type of object into another. For example, applying str to the integer 3 results in the string '3'.

What is a keyword?

　　Keywords are words that have special meanings within a language. Many editors will display them in special colors. These words cannot be used as variables.

What is the difference between a straight line program and a branching program?

　　A stratight line program simply goes through and carries out each step. A branching program will do differenct things depending on conditions set within the program.

What is a conditional?

　　A conditional statement starts with an if statement, and can also include elif and else satements.

基本上讲了一些完全初学者的内容，刚开始遇到这种问题的时候完全不知道怎么样答，因为这就是这。。。