不可数名词Air and water _____ important to us.谓语应该用is还是are?

不可数名词
Air and water _____ important to us.
谓语应该用is还是are?

are
这里涉及到主谓一致.以下是我以前的一点记录:
并列结构作主语时与谓语的一致关系
1.由and连接两个n.或pron.作S.时,A and B
1)A, B表不同的人、物或观念时,谓语v.用复数.Tom and Ann are good students. /Both Tom and Ann are here. (both A and B作S.时,谓语v.用复数)
2)A, B表同一个人、物或观念时,谓语v.用单数.A journalist and author lives in the courtyard. (一个记者兼作家的人住在这个院子)
3)A, B之前有each, every, many a, no…等修饰语,谓语v.用单数
Eacy man and woman is invited. /No boy and no girl is there now. /Many a boy and many a girl has been invited.
4)A, B为两个不可分的东西时,谓语v.用单数.A watch and chain was found on the desk. (一只挂表在桌上找到) /Bread and butter is nutritious. (奶油面包有营养)
2.由or, not noly…but (also)…, either…or, neither…nor连接S.时,谓语v.用就近原则
Either u or I am mad. /Neither u nor he is right. /Not only he but also his family were friendly to me.
3.当S.后有with, along with, together with, besides, except, like, including, as well as, rather than等词时,谓语v.不受词组影响,仅和第一个S.一致
All but one were here just now. (除了一个之外,所有人都在这儿) /A liberary with five thousand books is offered to the nation as a gift. /He as well as the others is going to the park. /The father, rather than the brothers, is responsible. (父亲和哥哥是负责任的) /He together with his brothers is about to help us.
单一主语的情况
1.以复数形式结尾的n.作S.时和谓语的一致关系
1)有些表示学科名称的词如：physics, maths, economics, news, means, works(工厂)等被认为是形复意单的词,作S.时谓语v.用单数.Every means has been tried.
上述n.如表示复数概念时,谓语v.用复数.All possible means have been tried.
2)表示双部分工具的名称、衣服名称等作S.时,谓语v.用复数,如：trousers/pants, shoes, glasses, scissors, goods, clothes
My trousers are white and clothes are blue.
上述n.如由pair(suit, piece, series, kind)+of修饰时,谓语v.用单数.A pair of shoes is lying there.
2.动名词、不定式、从句作S.时,谓语v.一般用单数.To see is to believe. /Reading is a good way. /When he will come is not known.
3.集体n.作S.时
1)mankind/humanity/man等作S.时,谓语v.用单数
2)people, police, cattle, youth等作S.时,谓语v.用复数
3)family, crowd, class, public, enemy等作S.时
a.当表示的人或事物当整体看,谓语v.用单数.Our family is very happy.
b.当表示的人或事物当若干个体看,谓语v.用复数.When I came into the room, his family were watching TV.
c.a family/group/class作S.时,谓语v.用单数；families/groups/classes作S.时,谓语v.用复数.A group is coming to us.
4.表示距离、时间、长度、价值、金额、重量等复数n.作S.时,谓语v.用单数
Three times three makes nine. (三乘三等于九) /Ten thousand pounds is a large sum. (一万英镑是一大笔钱) /Two hours is enough.
5.分数或百分数+of+词组作S.时,谓语v.取决于of后的n.或pron.的数
Three-fourths of the surface of the earth is sea. /Two-thirds of the people present are against the plan. /Tens of tons of waste goes into the air with the smoke everyday.
6.more than one作S.,谓语v.用单数.More than one boy has been there.
more than two作S.,谓语v.用复数.More than two boys have been there.
7.a (great) number of +复数n.作S.,谓语v.用复数
A number of the students are for the plan. /the number of +n.作S.,谓语v.用单数 The number of students in the computer class is limited to ten. (计算机课上学生的数目限制为十人)
8.the+adj.(表人)作S.,谓语v.用复数.The rich are for the decision but the poor are against it.
the+adj.(表物)作S.,谓语v.用单数.The beauty is hers.