這個詞組常用來指到某一點時間為止,主句常用完成時態(tài).具體如下：
1）從句用一般現(xiàn)在時,主句用將來完成時（will have done).
Bythe time I graduate next year, I will have lived here for 5 years. 到明年畢業(yè)時,我就在這里呆了五年了.
2）從句用一般過去時,主句用過去完成時.
e.g.Bythe time he was 12, he had traveled to more than 30 countries to get his diseases cured. 到12歲為止,他已去過三十多個國家治病.