Everyone has periods in their lives ______ everything seems very hard.
The country has acknowledged ______ every means to fight against any possible attack.
—What about saving the drowning boy from the other side of the river? —In my opinion,______.
______ two giraffes,Zheng He later brought zebras,shells,elephant ivory back to China after his voyages.
The official involved in the scandal said he was under ______ to make the false statement to the police.
—Do you like to buy the product an advertisement ______ on TV? —Not really.I think it's better to look before we leap.