题目

Northwoods Wildlife Center   Northwoods Wildlife Center is a non-profit organization based in Minocqua, Wisconsin, aiming to treat injured wild animals and return them to the wild.    In addition to caring for wild animals, Northwoods Wildlife Center also offers educational tours about wildlife and its staff members visit schools, camps, and festivals to educate people on how to live wit wild animals.   It operates without government funding(拨款), and relies entirely on donations from the public.   If you find wild animals in need of help, call us at 715-356-7400.  Teachers With用向上排空气法收集氧气时，要检验是否收满，可用________放在集气瓶的________，若________，则说明已满．