if条件状语从句的主句什么时候是一般将来时,什么时候是一般现在时主句，什么时候该用一般将来时（或一般现在时）？

通常用一般将来时 不通常用一般现在时 ——！ 这是废话

i will go hiking tomorrow if it is sunny.这属于从句用一般现在时，主句用一般将来时

1、在条件状语从句中,主句的时态是由时间决定的.动作发生在将来就用一般将来时,一般将来时的时间状语通常是tomorrow,next...之类的词.例如：如果明天不下雨,我们就去公园.
We will go to the park if it doesn't rain next Sunday.
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2、在条件状语从句中,如果住距是一般将来是、情态动词或祈使句,从句通常用一般现在时.例如：We will go to the park if it doesn't rain next Sunday.
He can come to see me if he has time the day after tomorrow.
Stay at home if you don't feel well tomorrow.

we use present tense in both if-clause and main clause for general fact or truth. For example, if we don't drink, we die. / if you frighten a dog, he barks.
we use present tense in if-clause but future tense (or can/may +v.) in main clause for possible futures, that is to say, when sth is likely to happen. e.g. if i'm free next week, i will go fishing with you.