I tell you I have never played tennis before.

我告诉你,我以前从未打过网球.
没有错!但是正确答案是 I told you I had never played tennis before 虽然我也认为原句是对的。但这之间有什么区别吗？I told you I had never played tennis before.-----我告诉过你的，我之前从没打过网球。 一般情况下，I told you...... 用得多。但单独这句：I tell you I have never played tennis before. 没有错啊！所以谈论一定要放在上下文中的。 希望对你有启发