说得对。这确实是一个“主系表”句型。当表语是表示人的心理状态的形容词（也可以是表心理状态的动词的分词，大多是过去分词）时，后面接从句，不定式短语或介词结构等说明心理状态产生的原因。 如；I'm sorry to have kept you waiting for a long time. He is proud that his daughter has been admitted to a famous university.
Hello, be afraid that 恐怕... ... 是引导的宾语从句（宾语有介宾和动宾）表示“恐怕”的内容，而表语从句时修饰表语的，要抓住从句的实质，连接表语从句的连接词有：that, what, who, when, where, which, why, whether, how, whoever，whomever，whichever ，whatever等，还有如because, as if, as though等，例：The question is when he can back.