It’s necessary for the phubbers(低头族)to______the time they spend on their smart phones.

Mark Twain, ____ his rich life experience, wrote many popular stories.

The man put out the cigarette when _______ thatsmokingwasnotallowedonthetrain.

Look! What are those boys doing ______ the table?—Well, they are playing cards

The post office is near here. You can go there _____ foot. You don’t need to go there _____ a car.