1） It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形， should 可省略。

句型：
(1)suggested
It is　(2)important　that…+ (should) do
(3) a pity

(1)suggested, ordered, proposed, required,　demanded, requested, insisted； + (should) do
(2)important, necessary, natural, strange
a pity,　a shame,　no wonder
(3)It is suggested that we (should) hold a meeting next week.

It is necessary that he (should) come to our meeting tomorrow.

2）在宾语从句中的应用
在表示命令、建议、要求等一类动词后面的从句中。
order, suggest, propose, require, demand, request, insist, command, insist + (should) do
I suggest that we (should) hold a meeting next week.
He insisted that he (should ) be sent there.

注意： 如suggest, insist不表示"建议" 或"坚持要某人做某事时"，即它们用于其本意"暗示、表明"、"坚持认为"时，宾语从句用陈述语气。
The guard at gate insisted that everybody obey the rules.　

判断改错:
（错）　You pale face suggests that you (should) be ill.
(对)　Your pale face suggests that you are ill.
(错)　I insisted that you ( should) be wrong.
(对)　I insisted that you were wrong.

3）在表语从句，同位语从句中的应用
在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气，即（should）+动词原形。
My idea is that we (should) get more people to attend the conference.
I make a proposal that we (should) hold a meeting next week.