题目:
Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).
选项:
A、acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate
B、acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating
C、act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating
D、they act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates
E、 they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate
答案:
A