一，数量被看成一个整体，动词用单数，如果看成该数量的个体，则用复数。
(1)six mouths is too short a time ,general westmoreland warned
(2)There were six silver dollars in each of the stockings.
二,如果主语的名词词组，由“分数+of--词组''其动词形式依of-词组中的名词类别定
(1)over sixty per cent of the city was destoryed in th war
（2) thirty-five per cenr of the doctors were wowen
三，两数相减或相除，动词用单数；两数相加或相乘，动词可单数可复数
(1)forty mnus fifteen (40-15) leaves twenty -five
(2)five times eight(5×8）is / are forty
四，"one in /one out of "+名词复数(正式);非正式可以按照就近原则使用动词的单复数
(1）one in ten student has failed the exam
(2） one out of twenty were badly damaged
A ，如果主语是all of ..，some of ...，none of...，half of ...，most of...，动词形式依据of后面的名词类别而定
a ，Most of mumbers were there
b，none but the best coffee is good enough
B，lost of ，heaps of ，loads of ，plenty of +名词；表示许许多多，随后的动词依据of 词组中的名词类别而定。
a，lost of food is going to waste
b，plenty of the men are already here
C，a series of ，a pile of ，a panel of+名词，a portion ，后面的动词用单数
c，aplie of logs was set beside the hearth
D,如果主语是”限定词+kind /type /sort of +名词"随后动词有以下变化
a kind of /sort ，this kind /type of 之后跟单数或不可数名词，动词用单数。
these kinds of ，mang /several kinds of 后面的名词可以是单数或不可数名词，也可以是复数名词，后面的谓语动词用复数，these kinds of insects are harmful 。
E,如果主语是many a +名词/more than one +名词；动词依据主谓一致，用单数
many a men has done his duty .
F,'an average of /a majority of "表示多数个体的概念随后的动词用复数，如果主语不表示多数个体概念，则动词用单数.
an average of 25persons apply each month
all average of 25applications a mouth is not unusual
