The socks are so ______ that they can’t be mended any more.

下列加点成语使用恰当的一项是：（ ）

When deeply absorbed in work，________he often was，he would forget all about eating or sleeping.

I shall never forget the day __________ Shen Zhou V was launched, _________ has a great effect on my life.

What else do you want to know about the cell phone— _______ it can be used as a digital camera. You know, I’m into photography.