Mass deaths of birds were not unheard of, but they normally happened unnoticed at sea or in rural areas away from towns. Many birds are weak and die in winter _______ food is scarce.
A．which B．what C．when D．how
There was no sign _______ they had died from diseases such as bird flu - the main worry in such cases. Among the theories was _______ a truck had collided（碰撞）with the crowd.
A．/; that B．that; that C．that; which D．that; /
Early this year, thousands of migrant _______ workers cancelled their insurance due to the lack of _______ policy to transfer insurance between difference regions.
A．the; the B．the; a C．/; the D．/; a
He handed in the essay two days later than his classmates，but it was still _____the time limit set by the teacher.
A．beyond B．within C．outside D．to
North Korea threatens to ________ from six-party talks aimed at ending North Korea's nuclear program unless its proper rights are to be satisfied．
A．escape B．flee C．withdraw D．retire
---Hey! Here is a message on my cell phone, telling me to send money to the bank account…
--Delete it! It's a trick. Many a person ________ by such tricks.
A．were cheated B．have been cheated
C．has been cheated D．was cheated
