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题目内容
（国家开放大学理工英语4）
people are no longer worried about whether their food is safe or not they enjoy a better life.
单选题 (10 分) 10分
A.
Only if……can
B.
If only ……can
C.
What if……can
单选题 (10 分) 10分
A.
Only if……can
B.
If only ……can
C.
What if……can
参考答案