While typing, Helen has a habit of stopping _____ to give her long and flowing hair a smooth.

A．occasionally

B．simultaneously

C．eventually

D．directly

按照( )分类，可分为平衡的通货膨胀和非平衡的通货膨胀。

A．物价总水平上涨的幅度

B．通货膨胀的原因

C．通货膨胀产生的原因

D．对价格影响的差别