这个问题可分为两个部分回答.
1.从句为宾语从句时：
1) 主句为一般现在时,宾语从句可用任何时态；
2) 主句为一般过去时,宾语从句要用相应的过去时态.即：过去将来时、过去完成时、过去进行时.
但凡是规则都有例外.宾语从句是客观真理时,时态保持不变!
e.g.Our geography teacher told us that the earth goes around the sun.
2.从句为状语从句时:
主句是一般将来时,时间状语从句、条件状语从句和让步状语从句中要用一般现在时表将来!
e.g.
1) The beauty will write to you as soon as she arrives in Beijing.
2）The beauty will e-mail you if she is loved by you.
3) The beauty won't be forgotten once (she is) seen.
当然：主句是一般将来时,时间状语从句中可用现在完成时表将来完成时.
e.g.
Don't get off the bus until it has stopped!