Birds are wonderful creatures that live in nearly every corner of our planet. They A ______ be of different colours, shapes and sizes. From the tiny hummingbird, which can flap B ______ wings more than sixty times per second, to the majestic eagle that C ______ high in the sky, each bird is a unique type. Birds play important roles in our ecosystems, such D ______ pollinating flowers, dispersing seeds and controlling insect populations Also they charm with their beautiful songs E ______ wonderful nests.