1. 加法：加法运算通常用and, plus, add 等表示。如：
Seven and [plus] eight is [are, make(s)] fifteen. 7加8等于15。
If you add ten to eight, you get eighteen. 10加8等于18。
2. 减法：减法运算通常用 minus, from, take (away) (from) 等表示。如：
Eight minus five is [leaves] three. 8减 5等于3。
4 from 20 leaves 16. 20减4余16。
Ten take away four is [leaves] six. 10减去4得6。(D8)
If you take five from twelve, you're left with seven. 12减去5得7。
If you take four away from ten, that leaves six. 10减去4得6。
3. 乘法：乘法运算通常用 times, multiplied by, twice 等表示。如：
Five times three is [equals] fifteen. 5乘以3等于15。
Five multiplied by two equals ten. 5乘以2等于10。
What is twice two? 2乘2是多少? (from www.yingyuyufa.com)
4. 除法：除法运算通常用 divided by, into 等表示。如：
Twelve divided by four is [makes] three. 12除以4等于3。
Four into twelve is [makes] three. 12除以4等于3。
