为什么“if it rains”后的“rain”很多答案上说要加‘s’,而很多有说是“if it will rain”到底哪个对?

为什么“if it rains”后的“rain”很多答案上说要加‘s’,而很多有说是“if it will rain”到底哪个对? i will stay at home if it rains this afternoon.这里为什么用rains? we won't go to the mountains if it rains tomorrow为什么要用rains? 关于We will go even if it rains.中的rainsWe will go even if it rains.中的rains为什么加S I am not sure if it___tomorrow.If it ___tomorrow,we wound not go for a picnic.中前一格填rains,那为什么后一格填will rain? Even if it rains tomorrow,we'll start out.为什么用Even if 为什么英语中只有“it rains heavily”而没有“it is rains heavily”的说法呢? But what happens if it rains?为什么happen要加sBut what happens if it rains?为什么happen要加s 男歌手的,高潮是When it rains rains rains it rains rains rains找出来追加50,决不食言 翻译：what if it rains tomorrow? it rains here in the summer .(often).(often)应该在 rains的前面还是后面?为什么? if it rains tomorrowIf it rains tomorrow 可不可以改成If it rainy tomorrow 做形容词、、? Do you know ____?A.if it will rain tomorrow B.if it rains tomorrow那个正确啊?为什么? Stay at home tomorrow if it is rains.为什么不能说成是Stay at home tomorrow if it will rain. We will not go rhere if it ____(下雨) tomorrow.横线上为什么填rains I will show you the garden if it stops raining.为什么不能改成stops rains. sometimes it rains 为什么填rains而不填rain? sometimes it rains和it rains sometimes 是不是一样的?