问题
选择题
You cannot take back your words ______ they are out of your mouth.
A．before
B．whether
C．once
D．while
答案
答案：C
题目分析：句意：一旦这些话从你的嘴里说出，就不能收回了。Before在……之前；whether是否；once一旦；while然而，选C。
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You cannot take back your words ______ they are out of your mouth.
A．before
B．whether
C．once
D．while
答案：C
题目分析：句意：一旦这些话从你的嘴里说出，就不能收回了。Before在……之前；whether是否；once一旦；while然而，选C。