the man we followed suddenly stopped as if

the man we followed suddenly stopped as if
①The man we followed suddenly stopped andl ooked as if______whether he was going in the right direction
.A.seeing B .having seen C.to have seen D .to see
【答案解析】显然,此题是考查as if的用法.As if ; as though作为一个固定词组,含有“好像”、“似乎”、“仿佛”、“宛如”等义,常用作从属连词,用来引导从句:.引导状语从句,修饰句中的谓语动词
选D.上面解释不懂.
请顺便帮我整理as if用法.
稍微简单点的概括归纳.

D.这题是as if 引导从句的省略现象.完整句应该是：
...as if (he was going )to see.
as if 的用法
as if 好像,好似 She spoke to me as if she knew me.她和我说话的神情,好像她早就认识我似的.(= as though)
as if 的用法
一、as if 从句的作用
(1)． 在look,seem 等系动词后引导表语从句.如：She looks as if she were ten years younger． 她看起来好像年轻了十岁.
(2)． 引导方式状语从句.如：She loves the boy as if she were his mother． 她爱这男孩,就好像她是他的母亲一样.The child talked to us as if he were a grownup． 那孩子跟我们谈起话来,像个成年人似的.二、as if 还可用于省略句中 如果as if 引导的从句是“主语＋系动词”结构,可省略主语和系动词,这样as if 后就只剩下名词、不定式、形容词（短语）、介词短语或分词.
如：He acts as if （he was） a fool． 他做事像个傻子.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.
三、as if 从句的语气及时态 (1)． as if 从句用陈述语气的情况.当说话者认为句子所述的是真实的或极有可能发生或存在的事实时.如：It sounds as if it is raining． 听起来像是在下雨.He talks as if he is drunk． 从他谈话的样子来看他是醉了.(2)． as if 从句用虚拟语气的情况.当说话人认为句子所述的是不真实的或极少有可能发生或存在的情况时.从句虚拟语气动词时态的形式如下：
1.如果从句表示与现在事实相反,谓语动词用一般过去时.如：You look as if you didn’ t care． 你看上去好像并不在乎.He talks as if he knew where she was． 他说话的样子,好像他知道她在哪里似的.
2.从句表示与过去事实相反,谓语动词用“had＋过去分词”.如：He talks about Rome as if he had been there before． 他说起罗马来好像他以前去过罗马似的.
3.从句表示与将来事实相反,谓语动词用“would／could／might＋动词原形”.如：He opened his mouth as if he would say something． 他张开嘴好像要说什么.It looks as if it might snow． 看来好像要下雪了.