英文句子 It can't have been Jill that you saw just now 什麼意思?

You saw Jill just now? It can't have been Jill.
你剛才看見 Jill ? 那不可能是 Jill 。

將兩句以 that 作引導便成為 It can't have been Jill [that] you saw just now. 你剛才所見的不可能是 Jill 。

不夠詳細。

you should divide this sentence to two parts. The key word in the sentence is "That".

That:
pron.
1. 那;那個,那人,那事,那東西
That's my English teacher over there.
那邊是我的英文老師。
2. (已被提到的)那個,那人,那事,那東西
Who told her that?
那是誰告訴她那件事的?

Apply to this sentence, the meaning is: 不可能是 Jill, 那人(jill)是你剛見到的

這無法是您看見剛才的Jill