并不是所有It is + adj + that从句的形式都用虚拟语气的.你这个句子只是一种陈述,而不是建议、愿望、请求、命令……等.
详细介绍如下：
在形如“It is (was)+形容词（或过去分词）+that……”结构中,使用某些表示愿望、建议、请求、命令、可能、适当、较好、迫切、紧近、重要等形容词后的主语从句的谓语也用虚拟语气.其表达形式为should ＋动词原形或省略should直接用动词原形（美国英语中省去should）
常用的形容词：* natural (自然的),appropriate (适当的),advisable (合适的),preferable (更可取的),better (更好的)* necessary (必须的),important (重要的),imperative (急需的),urgent (急迫的),essential (本质的),vital (必不可少的)* probable (很可能的),possible (可能的)* desirable (极好的)advisable（合理的）,compulsory（必须的）,crucial（紧急的）,desirable（理想的）,essential（必要的）,imperative（迫切的）,incredible（惊人的）,necessary（必要的）,possible（可能的）,strange（奇怪的）,urgent（紧迫的）.
常用的过去分词(Past Participle):* required (需要的),demanded (要求),requested (被请求的),desired (要求)* suggested (建议),recommended (推荐)* orderd (命令)
1.It is necessary that we (should 可省略,下同）have a walk now.(necessary,should + have) (表示有需要去散步)
2.It was necessary that we (should) make everything ready ahead of time.(necessary,should + make) (表示有必要事先做好准备)
3.It is required that nobody (should) smoke here.(required,should + smoke) (表示要求不要在此抽烟)
4.It is important that every pupil (should) be able to understand therule of school.(important,should + be) (表示重要的是学生都能了解校规)
5.It’s important that we (should) take good care of the patient.(important,should + take) (表示重要的是照顾好病人)
6.It is natural that she should do so.(形容词natural,should+动词原形do)
7.It is essential that these application forms be sent back as early as possible．这些申请表应尽早地寄回,这是很重要的.
8.It is vital that enough money be collected to fund the project．重要的是募集足够的钱,为这个项目提供资金.
9.It is desired that we（should）get everything ready this evening．希望我们今晚一切都准备就绪.
注：在上述所列形容词后面用that引出的宾语从句中,谓语动词也要用虚拟语气.
10.I don’t think it advisable that Tom be assigned to the job since he has no experience．汤姆缺乏经验,指派他做这项工作我认为是不恰当的.
二、在It is ＋名词＋that…的主语从句中的虚拟语气
在It is ＋名词＋that的主语从句中,常用虚拟语气,表示建议、命令、请求、道歉、怀疑、惊奇等.这类名词
有：advice ,decision ,desire ,demand ,idea,motion ,order,pity ,preference ,proposal,recommendation ,requirement,resolution,shame,suggestion,surprise,wish,wonder等.
⑴、It is my proposal that he be sent to study further abroad．我建议派他去国外进一步学习.