同学你好，该知识点来自沪江网校《BEC商务英语初中高级【四项全能实战签约班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学好
是的，通常情况都是要加句子的。
例句：
It seems as if our team is going to win.看来我们队要胜了。
She looks as if she were ten years younger. 她看起来好像年轻了十岁。

(as if引导的从句是“主语+系动词”结构，可省略主语和系动词，只剩下名词、不定式、形容词(短语)、介词短语或分词。)
例如：
Tom raised his hands as if (he was going) to say something. 汤姆举起手好像要说什么。
She left the room hurriedly as if (she was) angry. 她匆忙离开房间好像生气的样子。
He acts as if (he were) a fool. 他做事像个傻子。

祝学习愉快！