One way for students to prevent H7N9 flu virus is to open the windows of the classroom to allow the air to ________.
A.accumulate | B.circulate | C.illustrate | D.accelerate |
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One way for students to prevent H7N9 flu virus is to open the windows of the classroom to allow the air to ________.
A.accumulate | B.circulate | C.illustrate | D.accelerate |