疑问副词
中文翻译：如果
同义词：
['if', 'suppose', "what's the matter?"]
例句：
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1. If you don't finish your homework by tomorrow, you'll fail the test.
如果你明天之前不完成作业，你会考试不及格。
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2. What if she were here?
如果她在这里会怎么样？
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3. If it rains, we'll have to cancel our picnic.
如果下雨，我们得取消野餐。