首先,中学英语时态可分为两大类：present types（一现、现进、现完、一将）；past types（一过、过进、过完、过将）.其次,主从复合句表达中应考虑“时态呼应”原则,就时间状语从句而言：1、“主将从现”,即：含时、条状从的复合句中,当主句谓动为“一将”时,从句谓动应以“一现”替代、也可用“现完”.如：Tom will have a drink of milk before he goes to bed.Tom will do his homework after he has gone over his lessons.（从句行为结束后,接着进行主句动作）2、“过去对过去”,即：当主句谓动为过去时态时,从句谓动应取用一种相应的过去时.如：Mother was cooking when I reached home yesterday.（注意：“长短行为”,即一长一短两个过去行为并存时,一般用“一过”表达较短动作,用“过进”描述较长行为）.3、“（主）现完+since+（从）一过”.如：The Smiths have lived here since they came to China.对比：It is a long time since we met last.（强调“段时间”句型：It is + 段时间 + since 从句）. 首先,中学英语时态可分为两大类：present types（一现、现进、现完、一将）；past types（一过、过进、过完、过将）.其次,主从复合句表达中应考虑“时态呼应”原则,就时间状语从句而言：1、“主将从现”,即：含时、条状从的复合句中,当主句谓动为“一将”时,从句谓动应以“一现”替代、也可用“现完”.如：Tom will have a drink of milk before he goes to bed.Tom will do his homework after he has gone over his lessons.（从句行为结束后,接着进行主句动作）2、“过去对过去”,即：当主句谓动为过去时态时,从句谓动应取用一种相应的过去时.如：Mother was cooking when I reached home yesterday.（注意：“长短行为”,即一长一短两个过去行为并存时,一般用“一过”表达较短动作,用“过进”描述较长行为）.3、“（主）现完+since+（从）一过”.如：The Smiths have lived here since they came to China.对比：It is a long time since we met last.（强调“段时间”句型：It is + 段时间 + since 从句）.