1.如果我们在控制台中执行下列语句，结果分别是什么？为什么？ ``` >>> var a;typeof a; ``` ``` >>> var s = '1s';s++; ``` ``` >>> !!"valse"; ``` ``` >>> typeof -Infinity; ``` ``` >>> 10 % "0"; ``` ``` >>> undefined == null ``` ``` >>> false === ""; ``` ``` >>> typeof "2E+2"; ``` ``` >>> a = 3e+3;a++; ``` 2.执行下面的语句后，v的值会是什么？ ``` >>> var v = v || 10; ``` ``` >>> var v = 100; >>> var v = v || 10; ``` ``` >>> var v = 0; >>> var v = v || 10; ``` ``` >>> var v = null; >>> var v = v || 10; ``` 3.写一个打印乘法口诀表的脚本程序。利用嵌套循环实现。