also
ad.
1. 也,亦;还
John is also 19 years old.
约翰也是十九岁。
2. 同样地
Since you've accepted the invitation, I'll also accept it.
既然你已接受邀请,那我也接受邀请。
conj.
1. 又;并且
Also, he has gone abroad.
再者,他已去了国外。
▲also用于实义动词之前
They also agree with me.
他们也同意我的看法。
I also began to be interested in crickets.
我也开始对板球运动感到兴趣。
▲also用于be动词之后
I was also there.
我也在那儿。
He is also an American.
他也是美国人。
also用于第一个助动词之后
▲also用于第一个助动词之后
His sister has also gone to town.
他的妹妹也到镇里去了。
The leisure center has also proved uneconomic.
休闲中心业已证明利润不大。
also有时放在句首
▲also有时放在句子的最前
Also, some students were tempted to add written comment of their own throughout the paper.
一些学生也冒险通过论文写出他们自己的评论。
I thought it was the perfect answer. Also, Tony and I had never done a historical subject.
我认为它是完美的答案。而且，托尼和我从没有作过历史科目。
also不能放在句末
▲注意：also一定不能放在句子的最后。
参见：《柯林斯COBUILD英语用法词典》
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但是
赵振才教授在他的《英语常见问题解答大词典》中列举了美国英语关于also放在句末的例子。
I must buy some bread also.
我还必须买一些面包。
They know him and I know him also.
参见：赵振才《英语常见问题解答大词典》
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The son had gone also.
儿子也走了。
参见：张道真《现代英语用法词典》
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新诺亚英语网建议：
学生只要在阅读是不要少见多怪就好了，自己的作文中最好不要这样表达，以求保险。
too用于句子的最后
▲too用于句子的最后，可以有逗号，也可以没有逗号
"I'm feeling hungry." "Me too."
“我饿了。”“我也是。”
He's coming along too.
他也要来。
I have been to New York, too.
我也到过纽约。
She plays the piano, and sings, too.
她会弹钢琴, 也会唱歌。
too放在所指向的单词之后
▲too可以直接放在所指向的单词之后。
I wondered whether I too would become one of its victims.
我想我是否也会成为它的受害者之一。
We, too, are going away.
我们也要离开。
She, too, comes from Scotland.
她也是来自苏格兰。
too不能放在be动词之后
▲注意：too不能放在be动词之后，不能放在助动词之后，也不能放在句子的最前面。
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注意（一）：这里的too不是“也”的意思。
真正地；这样地：（indeed; so）
You will too do it!
你真的要做这件事情！
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注意（二）：
我国英语学界泰斗葛传槼在他的《英语惯用法》举了两个例子：
Too, your plan will save a lot of money.
You will go to the lecture, too, I shall go.
also,too,as well用于肯定句
在绝大多数的情况下，also, too, as well 只能用于肯定句。
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但是，葛传槼在他的《英语惯用法》举了以下的例子：
（可以说）He did not come, and she also did not come.
（不能说）He did not come, and she did not come also.
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