—I have to ask a(n) _____ of you because the luggage is too heavy for me.—Oh, with pleasure.

We have strong ________ for believing that the newly-invented material is not only popular but also a monument to the eco-friendly lifestyle.

Many kinds of birds fly south at the ______ of winter.

When you decide to start a family, you make a/an ______ to them. You shouldn’t turn your back on the people who love you.

Mrs. Obama introduced the Let’s Move _______ yesterday. Its goal is to reduce children obesity(肥胖) today and in the future.