We have very strict quality control and anything imperfect is________，so customers feel secure about our products.

After a careful survey about the cause of the newly-built bridge, they finally came to a(n) _________ that it was due to the heavy rain.

(2013·江苏，33)With inspiration from other food cultures，American food culture can take a________for the better.

Drinking water, having a healthy diet and taking exercise are all positive ways to ________ you when you are working on a tight schedule.

It was hard for him to learn English in a family, in which ________ of the parents spoke the language.