单项选择题
A．frightened B．guarded C．discovered D．caught
A．Taking a course on phenology. B．Knowledge of life cycle events of plants and animals. C．Efforts of ecologists to learn more about plant flowering. D．Full support of citizen scientists to study climate changes.
A．Topic—Comparison—Opinion B．Topic—Examples—Effect C．Question—Effect—Opinion D．Question—Cause—Effect