关于该句式中that从句的属性问题，人们颇有争议，但从语法的角度来看，无疑是表语从句。
1.  seem“似乎；好像”，是“连系动词”(link verb)，意义不完整，必须加表语构成复合谓语。例如：
She seems quite optimistic about it. 她似乎对这件事很乐观。
He seems to have something to say. 他好像有话要说。
2. “There seems ...” 可替代“There be...”结构，侧重说话者的“看法”或“臆断”。例如：
There seems no need to wait for her any longer. 看来没必要再继续等她了。
3. 在“It seems that/as if...”中，it是引导词，没有实际意义，指某种情况或现象；that/as if引导表语从句。例如：
It seems that/as if she has fallen in love with him. 看来她已经爱上他了。
注：①由于系动词seem的意义不完整，不能单独做谓语，所以上面的句子切不可去掉it而还原为：* That she has fallen in love with him seems.；用as if引导的从句作主语就更不对了。
②It seems 可换用It appears或It looks，但It looks后接 that从句较少见，要用as if/as though。
4. “It seems that...”可以转换成“名词或代词＋seem＋不定式”结构，意义不变。如果不定式为to be＋形容词，to be常可省略，但要注意时态。试比较：
It seems that he is ill. = He seems (to be) ill. 他好像病了。
It seems that he was ill. = He seems to have been ill. 他好像生过病。