1 . 要不是你去年努力学习，今天你也不会取得如此大的进步。（虚拟语气）
If ________ hard last year, you ________ such great progress today.

2 . If the rules of perspective had not been discovered, no one _______ paint such realistic pictures. (根据句意填空)

3 . ________ these spelling mistakes, I would have got a full mark in my English examination.

A．Because of

B．But for

C．In case of

D．In spite of