____time,Chinese farmers have invented many farming techniques.
| A．Over | B．In | C．On | D．For |
The Twins Days Festival, _______ began in 1975, is the largest annual gathering of twins.
| A．that | B．which | C．who | D．when |
—Have you started writing your report?
—Not yet．I _______ a hard time getting the information.
| A．am having | B．had |
| C．was having | D．will have |
The rainy weather lasted for a couple of days, completely _______ our plan for a picnic.
| A．being ruined | B．to ruin |
| C．ruined | D．ruining |
My grandpa has been enjoying good health ever since he _______ smoking.
| A．stops | B．stopped |
| C．has stopped | D．had stopped |
Working in the kitchen for years made Alice ______ a good cook．
| A．for | B．into | C．of | D．as |