为什么Maybe they are at home they 后面要用系动词be,而you may catch a cold ,may后面跟动词原形

Maybe they are at home同义句 为什么Maybe they are at home they 后面要用系动词be,而you may catch a cold ,may后面跟动词原形 Maybe they are friendly(Maybe) 同义句 改掉Maybe 是they at home还是they are at home为什么 :Unhappy,maybe nobody can make me happy at this time.Because they are falling asleep. ( ) books are these?Maybe they are Al( ) books are these?Maybe they are Alex's. They are very suprised at the news.为什么用at? They are at a camping site.为什么用at ,可不可以这样,They are a camoing site. Did you know _____ at the bus stop?maybe their teacher.a.who are they waiting for b.whom they are waiting for c.whom they were waiting for 这个题选择哪一个呢?我知道这个题应该是陈述句.但是我不知道为什么会选择C而不是 请教英语高手：1.My sister is good at (_),这里面为什么要填 boating,而不填play computer或 flies a kite 或 to draw pictures 2. () she is at home. 为什么要填 maybe 而不填 may be 3.Are they going to have a field reip tomorro they are sitting at a What are they good at? They are at the bus what they are staring at? Both of ___(they,them)are good at runing.为什么不是THEY? ( )they are not very delicious,but they are good for healthA:maybe B:although C:because what are they looking at a dog 为什么用look at they are so much better(to look at) than concrete.为什么不是be looked at