While ozone is a natural part of the Earth’s upper atmosphere, if it becomes concentrated in the lower atmosphere, it can potentially increase air pollution in areas where smog is a concern,

While ozone is a natural part of the Earth’s upper atmosphere, if it becomes concentrated in the lower atmosphere, it can potentially increase air pollution in areas where smog is a concern, (30)_______ can in turn impact the health of those living in these areas.

A. what

B. that
C. which
D. when

Trả lời

Chọn C

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