3.But if a treatment ________ delayed the disease by seven years were to be available, the number of sufferers would drop by 40% by the middle of the century.( )
21.Nowadays few people have the habit of keep a supply of candles in the house in case power failure. That was just what caused the confusion the another day. On Wednesday evening I was doing my homework at home when the light went out. Immediately I felt frightened, for I was lonely in the house. Then the telephone rang. She was Mom, who said she would back soon. I waited fearfully in the dark and gradually grew impatiently. Feeling my way to balcony, I knocked against a table and a bowl fall to the ground. It was not until 40 minutes later when Mom returned, complaining she had searched at least 5 stores before she bought the candles.