A good storyteller must be able to hold his listeners’ curiosity__________he reaches the end.

A．when

B．unless

C．after

D．until.

C处为平原，且降水丰富、灌溉便利，该地区的主要粮食作物是（　　）

A．水稻

B．小麦

C．大豆

D．燕麦