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.

单项选择题If I had () in business, I might be a very wealthy man today.

单项选择题As a party member, one should try to his duty.

单项选择题W expects to register its biggest Cyber Monday yet, coming off a record Black Friday weekend online.()

单项选择题The only games（）I play are football and tennis.

A.who
B.which
C.what
D.when

单项选择题They ( )the fire and crept into their tent.