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单选题
This cover will keep dirt, particles, or other unwanted material out of the system.
A
This cover will make sure that dirt, particles, or other foreign material are in the system.
B
This cover will keep dirt, particles, or other foreign material from entering the system.
C
This cover is the only method to separate dirt, particles, or other unwanted material from the system.
答案解析
正确答案：B
