The World Health Organization gave a warning to the public without any ______when the virus of H1N1 hit Mexico in April, 2009.
The boy decided to climb the mountains _______ he knew he would face many difficulties.
China has been pushing the reform of public hospitals _______ all its citizens.
In many people’s opinion, that company, though relatively small, is pleasant _______.
Let’s not wait any longer, he might not _______ at all.
Special attention should be paid _______ our earth from _______.