Not until all the fish died in the river how specious the pollution was.
| A．did the villagers realize | B．that the villagers realized |
| C．the villagers did realize | D．didn’t the villagers realize |
. They would not allow him _______ across the enemy line.
| A．to risk going | B．risking to going | C．for risk to go | D．risk going |
. There are so many kinds of tape-recorders on sale that I can’t make up my mind ____to buy.
| A．what | B．which | C．how | D．Where |
. Charles Babbage is generally considered _______ the first computer.
| A．to invent | B．inventing | C．to have invented | D．having invented |
. The missing boys were last seen _______ near the river.
| A．playing | B．to be playing | C．play | D．to play |
. The patient was warned _______ oily food after the operation.
| A．to eat not | B．eating not | C．not to eat | D．not eating |