英语语法9..为什么这是句强调句句子的成分分析下如果把it is.that 的结构去掉的话应该是什么

答：
正常句子：
Her parents gave her this IPhone 5 as a present on her birthday.
正常的强调句：
It was on her birthday that her parents gave her this IPhone 5 as a present.
然后有人根据已经掌握的情况,对这种说法加以反驳,指出：那件事不可能是在她生日那天发生的：
It couldn't have been on her birthday that her parents gave her this IPhone 5 as a present.
这是一个推测判断句.一般不会单独出现这样的句子,是人工考题句.实际生活中会根据上文,省略that后面的部分.
语境：大家在谈论某TX的IPhone,重点是什么时候买的.有人说是在圣诞节那天买的.
有人强调说：是在生日那天（不是圣诞节那天）
再有人反驳：不可能是在生日那天.这时候只需要说：It couldn't have been on her birthday.就行了.