a pair of, a couple of
一雙、一對
a pair of phr. "一雙···、一對···"指同一類的兩樣東西有機的結合在一起，缺一不可。
a pair of glasses
a pair of socks
a pair of compasses
a pair of 主要表示物件，有時也用來表示人或動物。
The happy pair on their honeymoon.
A pair of pandas have been presented to Japan.
a couple of phr. 單純指“一雙···、一對···或兩個同樣的東西”，可分可合。它的複數形式一般在末尾加s，也可不加。
a couple of rabbits
a couple of twins
a couple of 可以表示人或動物，也可以表示事物，表示人和事物時，是“兩三個、幾個”的意思。
Don't worry.We've got a couple of tickets left over.
in couple, in pair 表示“成對的、雙雙”的意思。
Please do it in pairs.
They are working in couples.
area,region,district
區、地區、區域
area n. 泛指面積較大的地區，但不是行政上的地理單位，如糧區、棉區等。
As you study a globe, you may notice that most of the large land areas are connected,or amost so.
area還可指能測量、計算的面積。
The Pacific is by far the largest occan and covers almost exactly half of the total ocean area.
region n. 指在地理上有自然界線，或具有某種特色，自成一個單位的“地區”，在這個意義上，它可以與area通用。但它也指較大的行政單位，如自治區、中南區、西北區和西南地區等。
There are three regions in Great Britain.They are English,Scotland and Wales.
Most of the forests are found in regions in the Northeast and Southwest.
district n.一般比region小，相當於我國的“區、城區”。
But Abraham Lincoln,who led the United states through these years,was murdered on April 14,1865 at theatre in Washington D.C.
Mr. Robinson appeared with nearly forty of the people of that district.
army,force,troop
軍隊、部隊
army n. “軍隊、部隊”，著重整體。
join the army 或 jion the forces 參軍
army在與navy和air force並列時，特指“陸軍”
Where did your sister study before she joined the army?
He explained that his friend was a Swede and knew no French; but he admired Napoleon so much that He wanted to join the French army and fight for him.
force n. 常用複數，是陸海空軍的總稱，著重力量和素質。
He says he's going to jion the air force and become a pilot.
The guards took the American to General Howe,commander of the British forces.
troop n. 一般不是表示一個整體的“軍”。如 to station troops（駐軍）中的“troop”不能用“army”替換。
The captain and his group moved on,but later that afternoon the main body of troops moved up toward the front,passing the place where the boy's body lay,covered with the flag.
