We'dbettereliminatejunkfoodsfromourkitchenandkeepavarietyofhigh-qualityfoods_____atalltimes.

Mrs Zhang often tells us that spring is the time ____ people go sight seeing.

The reason ____ (为什么这事情会这样)is now clear. I don't need to explain it once more.

Icanstillrememberthesittingroom____Iusedtositintheevening.

I still remember the days ____ we studied together.