I don’t think the problem you referred to is worth______.
In most western countries, on April Fool’s Day, people often play __ ___ trick on each other; children especially have great ______ fun.
-I’m thinking of the test tomorrow. I’m afraid I can’t pass this time. -_________! I’m sure you’ll make it.
Competitors are allowed to take a five-minute break every hour to eat,drink or do ________ is necessary
So far, all of the infected people are thought _______ the flu after direct contact with sick birds.
A number of high buildings have arisen ______ there was nothing a year ago.