How many________ do you need to finish thisarticle

I don’t think the film named　“Hero(英雄)”　is very exciting. — I don’t think it is，____________.

I feel it is Jack as well as his wife that _______ for their son’s bad performance at school.

My cousin Jack explained ____why he didn’tcome to our picnic.

Mountain climbing ________ be very tiring, and many people feel sick ________ the atmosphere gets thinner