If we travel a short distance, we should walk _____ taking a bus. Then we’ll be greener people.

对下列句子中加点词含义解释完全正确的一组是（ ）

hould have been warned not to cheat in the exam—_______, but he wouldn’t listen to me

What do you think of the report about the airpollution on TV last night—I think the situation is so thatwe should take action to protect the environment.

Maria _____ missed the first train so as totravel on the same one as John.