The Sanlu Milk Powder event is a clear indication that food safety is a big problem; nobody can __ _ all foods are secure to us, but we are sure that the situation is turning for the better.
Only then __________ how much damage had been caused.
—It’s burning hot today, isn’t it? —Yes. __________ yesterday.
So difficult __________ it to work out the problem that I decided to ask Tom for advice.
__________ homework did we have to do that we had no time to take a rest.
—Did Linda see the traffic accident? —No, no sooner __________ than it happened.