Thanks to biologists, we have learned a blot about hummingbirds. ___(21)___ the flying jewel, a hummingbird is a tiny bird with amazing flying abilities.　It can fly straight up in the air and even fly backwards and forwards. ___(22)___ its wings that it can remain hovering in one spot in the air.　___(23)___, a hummingbird’s wingspan is only four inches. Shockingly, the bird can rush through the air as swiftly as sixty miles ___(24)___ hour.　A hummingbird can travel far as well as fast. Small ___(25)___ a hummingbird is, it uses its unusual flying abilities to good effect.　When it discovers a flower with nectar, it flies straight to the flower and hovers in the air in front of the flower to drink from it.　After finishing drinking, it backs away slowly and ___(26)___ nectar in another flower.
【題組】21.
(A) Nicknaming　
(B) Nicknamed　
(C) To nickname　
(D) Nickname