The genetic engineering, ______ progress has been very rapid recently, is perhaps the most important of all the sciences．

Some old Chinese customs,       many of you are too young to know, have already died out．

She would say she was kept very busy, ____ she meant to refuse his invitation to dinner．

How long do you suppose ______ we applied for the job ________ we had been trained .

He came to a point ______ there was no more road to follow, and before him he could see nothing but a thick forest.

He has made progress in his English, _______ makes his father very happy.

I told you _______ that car, and now look what’s happened.

Is this the place ______ he used to live?

Alone in the garden sat the girl, thinking, for a long time, of _______ life was like with her teachers and classmates in the past. 

There are altogether fifty-four students in our class, _____ is a new comer from a faraway
mountain village.