名詞 are:

1. a unit of surface area equal to 100 square meters
   同義詞：ar

動詞 be:

1. have the quality of being; (copula, used with an adjective or a predicate noun)
   同義詞：be
2. be identical to; be someone or something
   同義詞：be
3. occupy a certain position or area; be somewhere
   同義詞：be
4. have an existence, be extant
   同義詞：exist, be
5. happen, occur, take place
   同義詞：be
6. be identical or equivalent to
   同義詞：equal, be
7. form or compose
   同義詞：constitute, represent, make up, comprise, be
8. work in a specific place, with a specific subject, or in a specific function
   同義詞：be, follow
9. represent, as of a character on stage
   同義詞：embody, be, personify
10. spend or use time
    同義詞：be
11. have life, be alive
    同義詞：be, live
12. to remain unmolested, undisturbed, or uninterrupted -- used only in infinitive form
    同義詞：be
13. be priced at
    同義詞：cost, be

1. Don't cry, you are a big boy now.
   別哭，你現(xiàn)在已經(jīng)是大男孩了。
2. These people who were young fifty years back are now gray haired.
   50年前的年輕人，現(xiàn)在已經(jīng)白發(fā)蒼蒼了。
3. Dark clouds are a sign of rain or snow.
   烏云是雨或雪將至的預兆。
4. There are 300 students or so in this middle school.
   這所中學大約有300個學生。
5. Love and hate are extremes.
   愛和恨是兩個極端。
6. There are more than 5,000 adjectives in that dictionary.
   那本詞典中有5000多個形容詞。
7. You are just saying that.
   你只是說說而已。
8. Who do you think you are?
   你以為你是誰？

are

v.（動詞）
Second person singular and plural and first and third person plural present indicative of be
be的第二人稱單數(shù)和復數(shù)以及第一和第三人稱復數(shù)現(xiàn)在陳述語氣詞

來源：
Middle English aren
中古英語 aren
from Old English aron * see er-
源自 古英語 aron *參見 er-

are
are 2

n.Abbr. a,a.（名詞）縮寫 a,a.
A metric unit of area equal to 00 square meters (9.' square yards).
公畝：面積的公制單位，等于00平方米(9.'平方碼）

來源：
French
法語
from Latin 3rea [open space] * see area
源自 拉丁語 3rea [開放空間] *參見 area