You'll never make progress in English you work hard at it.A.ifB.unlessC.whenD.fo
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You'll never make progress in English ________ you work hard at it.
A.if
B.unless
C.when
D.for
试题答案
B
You'll never make progress in English ________ you work hard at it.
A.if
B.unless
C.when
D.for
B