The number of the tigers is getting ________. If we don’t help them, they will disappear ______a few years

A．fewer and fewer, in

B．larger and larger, after

C．more and more, after

D．smaller and smaller, in

喷油器的功用是将喷油泵压送来的高压柴油经喷油嘴头上小孔以一定的射程和喷注锥角（）成较细的颗粒，并把它均匀地喷入燃烧室中进行燃烧。