The dictionary you need is on________shelf.After you use it,

The dictionary you need is on________shelf.After you use it,please remember to put it in_________place.
A.不填；the B.the；不填 C.不填；不填 D.the；the
There_________a great number of people waiting to buy the tickets
and the number of them_______increasing.
A.is；is B.are；are C.is；are D.are；is
It’s vital that we_______to carry out our health plans at once.
A.set out B.would set out C.will set out D.shall set out
请说明原因