For more than a decade, that certain species are becoming scarce. A. a warning for bird-watchers B. warn the bird-watcher C. the warnings of bird-watchers D. bird-watchers have war
For more than a decade, ___________ that certain species are becoming scarce.
A. a warning for bird-watchers
B. warn the bird-watcher
C. the warnings of bird-watchers
D. bird-watchers have warned