Third-person singular present of be

• Links subject to a complement to state identity or class
• States existence, condition, time, age, measure, or quantity
• Forms the progressive with present participles
• Forms the passive with past participles
• Used with a to-infinitive to express plan, duty, or arrangement

be 动词的第三人称单数一般现在时

• 作系动词，连接主语与表语表示同一或类别
• 表示存在、状态、时间、年龄、度量或数量
• 与现在分词连用构成进行时
• 与过去分词连用构成被动语态
• 与 to 不定式连用，表示计划、义务或安排

Introduces existence or occurrence, often with expletive there

• Presents or points out something newly mentioned

引入存在或发生，常与 there 作形式主语

• 首次呈现或提示某事物

Initialism of International Sign

• Initialism of information system(s)
• Initialism of international studies
• Initialism of implementation shortfall

“国际手语”的缩写

• “信息系统”的缩写
• “国际研究”的缩写
• “执行短缺”的缩写