if的条件状语从句的三种用法 1、主将从现（主句为一般将来时，从句为一般现在时）；2、主句含有情态动词（must、may、can etc.）从句为一般现在时；3、主句为祈使句,从句要用一般现在时态。 if从句的三种用法 1、主将从现（主句为一般将来时,从句为一般现在时）； eg:If it rains(从句) ,I will stay at home（主句）. =I will stay at home if it rains. 2、主句含有情态动词 （must、may、can etc.）从句为一般现在时； eg:If you drive too fast ,you may have an accident. =You may have an accident if you drive too fast 3、主句为祈使句,从句要用一般现在时态； eg:Don't play computer games if you don't finish your homework. 本文来源：https://www.wddqw.com/doc/6b0df6e6c47da26925c52cc58bd63186bdeb9275.html