1.If we run,we ---(catch)the early bus.2.She noe ---- ----a

If we run, we will catch the early bus.
She now serve as a math teacher in a high school.
再问： 原因
再答： if we run是虚拟语气，前半句用一般现在，后半句则是将来时。 第二个句子如果是两个空格的话，serve as就是作为。。。（职业）意思。