When television was first (introduced), the extent to (that) it would (affect) society could not (have been foreseen).

单项选择题(Annoying) at the long check-out lines, the shopper began (to sigh) loudly, tap his (foot), and (glance) at his watch.

单项选择题It (soon) became (obviously) that (instead of) (being trained) to sing she would be trained as a dancer.