The students’ exams, grades and marks should only be estimated by ______.

A．Because every species becomes extinct.
B．Because humans beings are powerful enough to kill other species.
C．Because of over-population.
D．Because human being is still a young species though it is exploiting the environment.

A．She was considerate.
B．She was unforgiving.
C．She was apologetic.
D．She was sympathetic.