If + Present Tense , S + Modal Verb
结构︰If + 现在式，主词+情态助动词
说明︰本句型实为句型之变体。之所以用情态助动词，主要是因为说话者对可能的结果不是太肯定或者是想表达例如必要的意思。
If it is fine tomorrow, we can go out.
如果明天天气好，我门可以出门。
If it is fine tomorrow, we could go out.
如果明天天气好，我门能够出门。
If it is fine tomorrow, we may go out.
如果明天天气好，我门可能出门。
If it is fine tomorrow, we might go out.
如果明天天气好，我门可能出门。
If it is fine tomorrow, we should go out.
如果明天天气好，我门宜于出门。
If it is fine tomorrow, we ought to go out.
如果明天天气好，我门宜于出门。
If it is fine tomorrow, we must go out.
如果明天天气好，我门必须出门。