高等继续教育 / 英语语法
正确率：100%
网络远程教育期末考试【英语语法】模拟试题
Although the causes of cancer ＿＿＿＿, we do not yet have any practical way to prevent it.
考题选项：
are being uncovered
have been uncovering
are uncovering
have uncovered
Although the causes of cancer ＿＿＿＿, we do not yet have any practical way to prevent it.
考题选项：
are being uncovered
have been uncovering
are uncovering
have uncovered
参考答案：