We have come to realize that the brain must “ forget” some pieces of information it can remember others.
A.when B.since C.so that D.if
They will not allow others to decide the future of their country,___ .
A.which is to be known B.as is to be known
C.as is known to all D.as what is known to all
, the climbers, who had already conquered many high mountains before, determined to reach the top of the mountain.
A.However it was high B.How high it was
C.However high it was D.However high was it
No one can tell the exact number of U.S. pilots and fighter planes were lost in the Pearl Harbor air attack.
A.who B.which C.that D.what
Travellers to that area can carry disease to their own countries that have never experienced_____.
A.them B.it C.themselves D.itself
The president hopes that the people will be better off when he quits than when he_______.
A.has started B.starts C.started D.will start
