在时间、条件、方式、让步状语从句中,常用一般现在时态表示将来.如：If it rains tomorrow ,we'll stay at home .We'll call you when we arrive in Beijing .
但是在名词性从句中,则要根据需要选用时态,该用一般将来时态的,就不要再用一般现在时态来代替了.典型题例：I don't know if it _______(rain) tomorrow ,but if it _______(rain),we'll stay at home .