Bicycling is a good exercise;________ it does not pollute the air.

I’m not good at English, my friend isn’t, ____.

Alan always gets up late and then goes to school, so he ______ eats breakfast.

—I saw you come to school by bus this morning.—Oh, I _______ come to school by bus, but it is raining today.

I don’t study as ______ as Amy and always make more mistakes in my homework．