It is necessary that a college student______at least a foreign language

The companies are working together to create _________ they hope will be the best means of transport in the 21st century.

The teacher said that they ______ hard-working students.

n is naughty, talkative,casual, but _____, his classmates think he is not so tiresome

_______ to a task calls for perseverance and concentration, if you wish for the final success.