If NASA is hiding intelligent alien life, what would be their reasons?

Bear in mind that, to an alien, America isn't the be-all and end-all.

If extraterrestrials visited Earth, they'd have turned up all over the place, not within the exclusive geopolitical boundaries of one nation. So it wouldn't just be the NASA/CIA axis hiding aliens, it would be a global conspiracy of space and spy agencies.

Likely? Not really.

Oh, I'd love to see evidence of extraterrestrial visits, particularly benign visits. But if they happen, we'll all know-I'm sure of it. These days, with smartphone cameras and global communications, it would be just about impossible to keep the lid down on that kind of struggling animal.

(Footnote In case anyone wonders: no-I haven't worked at NASA. As a researcher and alpha geek, I've processed NASA data since the days when I had 1″ magtapes couriered over to me from NASA Ames. These days, it's easier: I get them to take images of areas of interest, particularly the HiRISE camera on the MRO, and pick them up over the net.)

How would life on earth change if the moon were to be destroyed?

The places without artificial light would be totally dark. There would be no tidal waves meaning fishes would not come close to shore for people to catch it. It helps boats arrive to shore and without tides many harbors would be blocked.

Do Chinese people read science journalism?

Most of Chinese read news from internet nowadays. So most of science news read are those interesting ones on the websites, Weibo, Weixin, as other answers have told so.But many Chinese men like myself and some women enjoy military science and technology magazines.The three most sold and  subscribed are called "The Three Knowledges".They are

What are best trekking operators in India? I've heard Indiahikes is good but they're usually full and they don't conduct few interesting treks.

Seriously saying there are no such best trek operators in India. All trek operators are just milking money out of a poor guy who dreams of putting a foot outside his known boundaries. I have firsthand experience with Indiahikes or trekthehimalayas some years back .They made batches each having a min of 30–40 people.