---Do you still remember when we went to Chong qing?
----I can’t remember now but_____ sometime last summer?
A．could it be B．might it be C．must it have been D．could it have been
The demand that the law on gun ownership _____ be changed ___ is very strong.
A．changes B．will be changed C．be changed D．be changing
The increase of the number of the students makes the limited computers not ________ to each student.
A．available B．helpful C．acceptable D．affordable
He had just sent an email to his pal on the Internet ________ the system broke down.
A．while B．when C．after D．since
While intelligent people can often ______ the complex, a fool is more likely to complicate the simple.
A. sacrifice B. substitute C. simplify D. survive
People develop ________ preference for a particular style of learning at ________ early age and these preferences affect learning.
A. a；an B. a；不填 C. 不填； the D. the；an
