The University of Minnesota claims that in 12 half-hour lesson______.
A．it can double a student's reading speed
B．it can triple a student's reading speed
C．it can increase a student's reading speed four times
D．no real increase in reading speed can be achieved

单项选择题We offer you our lowest price, ( ) we have done a lot of business with other customers.

单项选择题We hope you will see your way (clear) to ( ) your price.

单项选择题Everybody in the class must give in () exercise book within the given time.

单项选择题The law requires all cars () for safety and efficiency.

单项选择题The weight of something is another way of describing the amount of force exerted on () by gravity.

单项选择题Prior () his departure, he wrote a letter to his mother.

单项选择题The owner of the store promised to give the money back to the traveller（）his return.

A.at
B.from
C.by
D.on

单项选择题Only after I left the place that how ugly and dishonest the people there had been.

单项选择题When the clouds moved in, the moon was no longer () sight.

单项选择题Going () sleep for a long time makes me feel very tired.