Only when you have acquired a good knowledge of grammar,_____write correctly.

问题描述:

Only when you have acquired a good knowledge of grammar,_____write correctly.
A.can you B.can’t you
C.you can D.you will

选A,only+短语或句子,用于句子开头,句子要用局部倒装语序.
句型为:only+短语或句子+助动词/系动词/情态动词+主语+谓语+其他成分
翻译:只有当你掌握了语法知识,你才能写的正确.