华北平原是我国典型的____。
A．一熟地区
B．两熟地区
C．三熟地区
D．四熟地区
参考答案：C
The couple finally bought the house they wanted, for they______enough money.
A．had saved
B．were saving
C．would save
D．were to save
广义表L=(a，(b，()))的深度为______。
