—Do you know the reason why he failed ?—No, he’s a hard-working man___________, he failed finally.

. ______we’ll be able to drive a car______ by electricity, solar energy in about ten years.

The lecture is so attractive that the audience are listening_________.

When Helen saw his tutor nod ________ to her, she calmed down and went on with her performance. 

I was caught in the traffic jam this morning; ______, I would have come on time.