People have come to understand _____ prevents so many Americans from  being as happy as one might expect.

It was not until the early 1950s ______most tape recorders began using plastic tape as they do today.

—The patient looks much better.________ is it that has made him ________ he is today?—Perhaps the special medicine and his family's patient care.

 It was after he got what he had desired_____ he realized it was not so important.

—Who is making so much noise in the garden?　　　　—______ the children.