Years ago we didn't know this, but recent science ______ that people who don't sleep well soon get ill.
| A．showed | B．has shown | C．will show | D．is showing |
79.I was disappointed with the film . I had expected ______ to be much better.
| A．that | B．this | C．one | D．it |
80.It was not until 1920 ______ regular radio broadcasts began.
| A．while | B．which | C．that | D．since |
81..______is a fact that English is being accepted as an international language.
| A．There | B．This | C．That | D．It |
82.I was only when I reread this poems recently _____ I began to appreciate their beauty.
| A．until | B．that | C．then | D．so |
83.I hate___ when people talk with their mouths full.
| A．it | B．that | C．these | D．Them |