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一、加 
 
英语的“加”叫add,来自拉丁语addo,ad即“to”; do “put”合起来即put to,也就是“加上”。请看以下add的用例: 
 
Add 360 to the total. 在总数上再加360。 
 
The costs added up to 1000 dollars. 费用总计为1000美元。 
 
First, we add water;next we boil. 我们先加水,接着把水煮开。 
 
注:类似“3+4=7”这样的算式,可用以下包含add的英语句子表达: 
 
Three added to four makes seven.  
 
Three and four add up to seven.  
 
If you add three to four, you get seven.  
 
  
 
二、减 
 
减,英语subtract,来自拉丁语的subtractus;sub即“away”; tractus “taken”。“减”就是“take away(去掉)”。请看以下用例: 
 
If you subtract 3 from 5, you get 2. 五减去三就得二。 
 
My son has begun to learn to add and subtract. 我的儿子已在学做加减法了。 
 
  
 
三、乘 
 
“乘”叫multiply,来自拉丁语的multiplico;multus是“many”的意思;plico, “fold(倍)”,multiply即“manifold(多数倍的)”。请看例句: 
 
Five multiplied by three is fifteen. 5乘以3等于15。 
 
表示两数相乘时,除可用multiply, 也可用times。如:(from www.yywords.com) 
 
Five times eight is forty.  
 
=Five multiplied by eight is forty. 5乘以8等于40。 
 
注:在Five multiplied by eight is forty中,multiplied by eight为修饰five的过去分词短语(用作定语;句子主语是five),其中的multiplied不能换成multiplying或to multiply等。比较: 
 
If you multiply 7 by 15, you get 105. 如果用15乘以5,结果是105。 
 
  
 
四、除 
 
“除”叫divide,是“分开”的意思,来自拉丁语的divido; di即“apart”;vid-, “separate”。请看用例: 
 
If you divide 20 by 4, the answer is 5. 如果你把20除以4,那么商就是5。 
 
Ten divided by five is two. 10除以5得2。 
 
Three will not divide into eleven. 三除不尽十一。 
 
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