Question

2．I would like to take this opportunity to thank my leader，without whose support/and without his supportour program
could not have been completed so smoothly．（support）
我想借此機會感謝我的領導，沒有他的支持，我們的計劃不可能這么順利地完成．

Answer 1

分析 I would like to take this opportunity to thank my leader，without whose support/and without his support our program could not have been completed so smoothly．

解答 本句主句是表達自己的感激之情，用一般現在時，從句表示對過去事實的虛擬，所以用虛擬語氣．
本句可以用一個定語從句without whose support our program could not have been completed so smoothly來修飾先行詞my leader，也可以加上連詞and構成一個并列句．
take this opportunity to do sth利用這個機會做某事；could not have done sth意為"本來不可能完成某事"．

點評 另外，but for，otherwise等均可引導含蓄虛擬條件句．如：
But for your help we couldn't have succeeded in the experiment．如果沒有你的幫助，我們的實驗是不會成功的．（=If it hadn't been for your help，we…）
I'm really very busy，otherwise I would certainly go there with you．我真的是太忙了，不然我就會同你一道去了．（otherwise=if I were not so busy）