Radar enables the pilot of an airliner to take off, fly and land in _____.
—What do you think of being a volunteer, John? —I find it a stressful job but one ___ you can really help people.
—Is there anything wrong, Bob? You look sad. —Oh, nothing much. In fact , I ____ of my friends back home.
It is not always easy for the general public to see _____use a new invention can be of to their daily life.
More highways have been built in China, ______ it much easier for people to travel from one place to another.
To her joy, Della earned first the trust of her students and then ____ of her colleagues.