变量是在赋值时动态键入的，因此不需要预先声明变量或者使用 new运算符。
Variables are dynamically typed on assignment, so there is no need to pre-declare variables or use the new operator.
用户在City Name字段中键入文本时，将动态显示建议，类似于Google的自动建议功能。
As the user types text in the City Name field, Suggestions are dynamically displayed, similar to Google's auto-suggest.
表达式计算器可以计算作为动态而静态键入的变量。
The expression evaluator can evaluate variables that are statically typed as dynamic.
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